Manhunter. Hannibal Lecter informs Will Graham of this.
Lecter: You want the scent? Smell yourself.
Luke Skywalker of Star Wars gets his Not So Different moment when he cuts off his father's artificial hand. Luke sees that he has just repaid Vader's violence in kind, but also sees his own prosthetic hand as symbolizing the possibility that he's becoming like his father. This was foreshadowed earlier in The Empire Strikes Back, when Yoda sends Luke into a cave to be attacked by a masked warrior brandishing a lightsaber, looking much like Darth Vader. Luke quickly defeats the warrior, decapitating it. The warrior's mask falls off, and its face is exactly like Luke's. Yoda pointed out before Luke went in that the cave only contains what you take into it (i.e. it shows you yourself, and your weaknesses) in fact telling Luke he won't need his weapons. Luke completely ignored him, leading to that sequence.
Occurs twice in the Austin Powers trilogy, between Doctor Evil and Austin (who, amusingly enough, are both played by Mike Myers); first in the first film near the end, and later in the third film:
Doctor Evil: Remember when I said 'We're not so different, you and I'? Cuts back to the first film, with Austin aiming his gun at Doctor Evil. Doctor Evil: We're not so different, you and I. Flashback ends. Doctor Evil: See? I did say that. Austin: Yes, very nice. Now where's my father?
The third film also reveals that Doctor Evil and Austin are twins proving that they are Not So Different in more ways than either believed.
Belloq: You and I are very much alike. Archeology is our religion, yet we have both fallen from the pure faith. Our methods have not differed as much as you pretend. I am but a shadowy reflection of you. It would take only a nudge to make you like me. To push you out of the light.
Bill Corbitt: The "we're not so different you and me" speech is copyright Ben Gazzara. It cannot be used without the express written consent of Ben Gazzara.
Indiana Jones and the Last Crusade: Dr. Elsa Schneider serves as the ambitious, female foil to Indiana. After she reveals her allegiance with the Nazis, she says to Indiana, "We both wanted the Grail. I would have done anything to get it. You would have done the same" to which he replies, "I'm sorry you think so." At the end of the film, their actions mirror each other. Elsa finds herself suspended over an abyss, with Indiana having caught her before she fell in. Rather than let him save her, she tries to reach for the grail underneath her. Indiana can't maintain his grip on her gloved hand, and she ultimately plummets to her death. Moments later, Indiana also tries reaching for the grail, despite what he had just witnessed. It took a You Called Me X, It Must Be Serious moment to break him free of the grail's allure.
Mr. Potter: Look at you. You used to be so cocky. You were going to go out and conquer the world. You once called me "a warped, frustrated, old man!" What are you but a warped, frustrated young man? A miserable little clerk crawling in here on your hands and knees and begging for help.
Inverted in Galaxy Quest, where the villain forces the main character to explain how he's Not So Different from the villain... to an ally who hero-worships the main character. Once shown the "historical documents" Sarris is the only nonhuman character who actually realizes that he is dealing with actors who have been mistaken for real explorers. This implies that unlike the Thermians, his own race produces entertainment. This creates a bit of Fridge Horror when you realize the Big Badcan empathize with humans more than the kind, gentle Thermians.
Bond: "There's a useful four letter word. And you're full of it. When I kill, it's on the direct orders of my government. And the men I kill are themselves killers."
Also in the Bond series, but much more overt, is the subtle comparisons of Skyfall villain Silva to both Bond and M. Silva is shown to be well-spoken, manipulative, and charming. He's also shown to be quick to dispose of things like Severine that are no longer of use to him. M herself said that he was "a brilliant agent."
The Kingdom is an interesting version, having a Not So Differentending. At the very end of the movie, it is revealed what the hero said in the beginning when whispering a reassurance to another member of his team "We're going to kill them all", referring the Diabolical Mastermind terrorists who executed an attack that killed at least one of their coworkers. Just after this revelation the film cuts to that terrorist's grandson, who heard his last words after the terrorist was fatally shot. Asked by his mother what his grandfather's last words were, the young boy replies that they were "Do not worry, my child. For the day shall come when we kill them all".
Spoofed in a deleted scene from Small Soldiers when the protagonist's slightly obnoxious neighbor and his family is being held hostage by sentient toys:
Phil: You know, we're not so different you and I. I have been accused of being plastic all my life!
Major Chip Hazard: "You've got a lot of guts. Let's see what they look like!" (attacks Archer)
Archer: "They're wires and metal, the same as yours."
Major Chip Hazard: "We're nothing alike. You are programmed to lose."
In Falling Down, an odious Neo-Nazi shopkeeper tries to use a Not So Different speech with the insane vigilante protagonist.
Nick: I'm with you. We're the same, you and me. We're the same, don't you see?
Reverend Mother in The Trouble With Angels says it's one of the reasons she decided at the last minute not to expel troublemaker Mary: both are strong willed, and Reverend Mother says she can't be less tolerant of Mary than the Church has been of her.
In David Lynch's Blue Velvet, insane drug-addicted rapist Frank hisses "you're like me" at the story's young hero Jeffrey Beaument.
In District 9, we have this scene when the main character, already in his alien form, is hiding in the nice alien's house. The nice alien kid likes the main character, because they're the same.
Batman uses a not-so-different Speech to try to reason with Catwoman near the end of Batman Returns in hopes of demonstrating that he understands her struggle with an alter ego that deliberately rejects hope for a happy life. Awareness that he is not so different from the Penguin as Batman and from Max Shreck as Bruce Wayne is also hinted at being his reason for taking his battles against them so personally.
Shinzon hits Picard with this repeatedly in Star Trek: Nemesis. Seeing as he genetically is Picard, but with a vastly different life, it's understandable that the idea unsettles him something fierce. However, the movie is notable for how once he gets a handle it, Picard makes a game attempt to turn it around on Shinzon: Rather than stressing how far removed he is from villainy, he tries to show how Shinzon could cross the "not so different" gap for the better. It doesn't work. Shinzon's nuts.
In Zulu the Men of Harlech scene where the Welsh and the Zulus are singing their tribal Proud Warrior Race songs to each other before killing each other.
Inverted in Dogma, when Bethany, the Last Scion, unknowingly has a conversation with fallen angel Bartleby, whom she's been recruited by Heaven to fight against. They talk about each other's problems, the frustrations of life and how much they have in common, and it's only near the end of the conversation that Bartleby realizes who she is. The stage seems set for Bartleby (who, so far, has been a reasonable and sympathetic foil to his more villainous partner Loki) to learn that we're all in this together and everyone has the same problems. Instead, he's infuriated that humans are oblivious to being favored by God over the angels, and their conversation leads him to try to Put Them All Out of My Misery.
In the climax for Time Cop, when McComb, the corrupt politician, mentions that Max Walker's attempts at stopping McComb (who in the process of going back in time to ensure he won the Presidential elections, also arranged for the murder of Walker's wife) made him as bad as himself. Walker contradicts him, however, stating that he was actually attempting to set the timeline right.
The protagonist of the first Mad Max has a minor Heroic BSOD over the thought that he might be sliding into this trope, and/or its close relative He Who Fights Monsters. Then said monsters murder his wife and child, after which he's past caring about either trope.
Turned on it's head in Under Siege, when protagonist Ryback give the speech to antagonist Strannix.
In The Truman Show, after a heated and bitter on-air callback confrontation, both Sylvia and Cristof stroke Truman's image on the monitor, suggesting that for all their differences, they genuinely love and care about Truman in their separate ways.
In Mean Girls, Janis wants revenge on Regina and is as manipulative and spiteful as Regina. It brings an interesting interpretation as Janis used to be the queen bee in her old school and Regina was the innocent friend (like Cady) who was slowly evolving.
Later when Xavier is shot and Erik/Magneto is speaking to him, the following conversation takes place:
Erik Lehnsherr: Us turning on each other, it's what they want. I tried to warn you, Charles. I want you by my side. We're brothers, you and I. All of together, protecting each other. We want the same thing.
Charles Xavier: My friend. I'm sorry, but we do not.
In a good way, the American and Soviet sailors. Every scene with the American navy is almost immediately mirrored by the Soviet navy (or vice versa), showing that they had the same reaction or feelings. Both have a strong sense of honour and discipline and both are reluctant to shoot first and provoke World War III. The most obvious may be their It Has Been an Honor moment where Magneto fires their missiles back at them.
Averted in Circuitry Man where androids are genetically and biologically engineered lifeforms. The villain "Plughead" and the hero Danner are both androids. Plughead spends every moment trying to kill Danner and get back his Maguffin. In a virtual reality world it comes to a head when Danner is going to kill Plughead. Plughead realizes he's outmatched and tries to save himself with a "you're just like me". Danner looks like he's going to turn away when he responds with "Yeah, maybe just a little" and stabs Plughead through the heart
Zen Noir contains a non-villainous example. The story concerns a private detective investigating a death at a Buddhist temple. At one point the detective insists to the oldest monk that he is completely different from the monks and doesn't understand them at all. The monk interrupts to ask for the detective's fedora. Eventually the detective gives it to him, revealing that the detective is almost entirely bald under the hat. "Not so different" says the old monk with the shaved head... who then puts on the fedora and sets it at a stylish angle.
In the Apocalypse film series movie Tribulation, Franco Maccalusso's Digital Avatar tells Helen Hannah that, as Lucifer, he used to be God's chief angel until he realized he was just like God. Helen Hannah refutes it by saying God loved the world and died for His world while Lucifer (by extension of Maccalusso) wants people to die for him.
The Avengers shows similarities between Tony Stark and Loki. Both are clever but have little idea how to fight beyond Attack! Attack! Attack!. Both are narcissistic, Deadpan Snarkers, prone to self-destructive behavior and bitterly jealous of the blondnobler teammate who their father liked better. The only real difference is that Tony learned the hard way to care for and rely upon others, while Loki did not. Tony himself says it best.
Stark: And Loki, he's a full-tilt diva, he wants flowers, he wants parades, he wants a monument built to the sky with his name plastered-
Stark: Son of a bitch. (A dual realization: That he was this trope to Loki and that Loki will use his Stark tower to summon the Chitauri.)
There was an interesting scene in the film version of The Hunger Games where Foxface and Katniss bump into each other while running away from the slaughter at the Cornucopia. They stare at each other in terror for a second before silently bolting off in different directions.
In Safe House Tobin Frost sees himself in the CIA Agent Matt Weston, back when he was a naive CIA Agent himself.
In The Quick and the Dead, Herod reveals to Lady that Cort use to be just as much of a coldblooded murderer as himself. So much so, that there was a time the two were looked at as the same. When Lady asked him if it was true, Cort said: "Yes."
Something of a recurring theme in Battle: Los Angeles: Some Marines spot an alien commander spotting for two alien snipers on top of a roof. Lenihan surmises they may be just like them — grunts with families and a home, with no idea what's really happening and just get told to go fight.
Displayed as well — several scenes show downed enemy aliens being dragged away back into cover by their squadmates, with the others providing covering fire. Just like what human soldiers do. The directors made it a big deal that the aliens used human tactics.
A subtle case of this pops up when the scientist discusses how the aliens are using "colonization" tactics on humanity. Though not outright stated, there's an implication that we know the aliens are using colonization tactics because mankind used them too.
In Mulholland Falls, the general draws a that connection between himself and Max during their first encounter on the military base.
John Harrison in Star Trek: Into Darkness noticed Kirk's love for his crew and presented his own love for his crew as a point of similarity between them. Not to mention how both of them are willing to go great lengths to protect and save their crew. Also, throughout the movie, Kirk and Harrison have the desire to avenge their loved ones, Harrison against Admiral Marcus for supposedly killing his crew and Kirk against Harrison for killing his mentor Pike. But whereas Kirk, with the influence of his crew, learned that he shouldn't let revenge cloud his judgement and refused to kill or even stun Admiral Marcus since his daughter was watching, Harrison let his hatred for Starfleet fester and didn't care if innocents got caught in the crossfire.
In Hellraiser III: Hell On Earth, Pinhead gives Monroe a speech about how the way he derived pleasure from devouring the girl is no different from Monroe wooing her to have his way with her sexually and then throwing her out while mocking her. Monroe denies it violently.
The first appearance of the three-headed alien dragon King Ghidorah was in a 1964 flick called Ghidorah the Three Headed Monster. In one scene in the movie, Mothra starts pleading with Godzilla and Rodan (who seem more occupied with fighting each other to be concerned about Ghidorah) to help her fight the larger threat, while Mothra's tiny handmaidens translate the conversation to the humans viewing. And it would almost seem funny if not for the crisis. Both Godzilla and Rodan blame each other for starting the fight and neither is willing to consider an alliance until the other apologizes. Eventually, one onlooker comments that "These monsters are as bad as humans."
The Heat Mullins and Ashburn are both law enforcement officers that are extremely good at their jobs, but are despised by their peers due to their grating personalities.
They also both have family issues.
In The Lone Ranger Cavendish pretty much says this word for word when He discovers the Ranger is actually John. He says they're both men that have to wear masks, implying that he's had to maintain the secrecy of things he's done.
At the end of The Crossing, Washington initially refuses to accept the dying Colonel Rall's surrender personally (a "courtesy of war") because the Hessians are mercenaries who fight for profit and have committed atrocities against his men. General Greene changes his mind by pointing out that their cause was founded in part to resist English taxation—so really, everyone is fighting for profit.
A silent one at the end of The German: The titular character offers his foe, Red Leader, a cigarette as a peace gesture after both have been taken into internment by the neutral Irish authorities.