Our shero just recently noticed that the partner she patrols the city with is just like the guy in her lacrosse club. She could even mistake them for being the same guy the way she's never seen them together. They're both big, goofy, listen to the same music and have a wife named Alice. Further observation reveals that she never sees them together because they don't have much in common that isn't superficial. They are both have afros but Bob buys his hair care from grocery store, Steve makes his own. Bob works out at the gym to stay in shape for his job, Steve is a farmer whose job keeps him in shape. Bob is a night owl, Steve goes to bed at sunset and while Bob's likes to poke fun at things Steve is more of a practical joker. Our hero hunts the agents of corruption with unrelenting zeal and shows his prey no mercy. He's come to learn of another hunter who he has much in common with and believes to be a valued ally. They hunt the same prey using the same weapons, they both wear long coats with sunglasses at night and one night they finally met. It also turns out that both are Not So Different from their common enemy either but for different reasons. Our hero has been exposed to the same corruption they work for. This other guy is more like them in his behavior. Our hero shows no mercy for the enemy only to make sure they harm no innocents. The other guy doesn't believe in innocents and will kill a target just to spite the agents. Our hero will drag his prey away from populated areas to minimize casualties and property damage. The other guy is a Destructive Savior on his best day. Our hero believed they were allies fighting for the same cause but it turns out his "ally" sees him as another trophy to be mounted on his wall. Two characters, groups or otherwise may appear to be alike, they may even be able to fill the same niche in a story but it would be a mistake to go so far as to call them interchangeable and if given the opportunity they'll let you know it. If not, those who know them well will. Expect one party to begin with "I'm nothing like ___! Common cases include Cloning Blues, Shadow Archetype, and Legacy Character. Counterpart Comparison is when fandom does this.
- In general, if the isn't claiming the product in question isn't a more affordable version of the competition then they are using this trope, such as when Verizon Wireless, and AT&T, two American phone companies who used to have a friendly relationship, broke away from each other. They both quickly dedicated much of their budgets to letting everyone know why they should never be mistook for the other.
- Between the 1910s and 20s Coca Cola became well known in several countries and also became frequently imitated. The most humorous duplicates being Sola Cola and Coc Ola. Naturally, many commercials were put out explaining to the consumer why these knockoffs were inferior to the real thing.
- Piccolo and Vegeta from Dragon Ball, two evil aliens who became friends with Goku. Piccolo initially saw Goku as an obstacle to World Domination, Vegeta just had an obsession with becoming the strongest and Goku's existence got in the way. Also, Piccolo's friendship was genuine, even if he hated to admit it. Vegeta didn't bury the hatchet until the entire universe was at stake. Piccolo at one point has to explain Vegeta's own problems to him.
- Issac McDougal attempts to recruit Zolf Kimbley, another State Alchemist who killed his superiours and apparently defected, in the first episode of Fullmetal Alchemist: Brotherhood. However, while both are defectors from the military and use their alchemy to attack opponents from within (freezing and exploding, respectively), McDougal is a Defector from Decadence who wants to save Amestris from the Ancient Conspiracy, while Kimbley is an Ax-Crazy Nietzsche Wannabe.
- In Neon Genesis Evangelion, Rei and Kaoru have an exchange that amounts exactly to him discussing Not So Different and she invoking this.
- Blade felt he had a lot of similarities with The Punisher but had to question why Frank Castle pursued a seemingly impossible goal while Blade felt his own was much more reasonable(He even succeeded once already). In Frank's answer Blade(and the readers) start to understand just how different they really are.
- In a meta sense, Marvel gave Blade to a popular Wolverine writer hoping he could duplicate that success. It was made clear that they weren't really that alike.
- In the various DC-Marvel crossovers, although both universes have a planet Earth which is inhabited by a human species with broadly similar histories up to about the 1960s, it's been shown that they're fundamentally different down to even the background cosmic principles each is based on.
- Data has to explain why Captain Picard shouldn't expect his clone to be much like him Star Trek Nemesis. As a robot, he is just one of many of his line but he knows just because the rest have the potential to be just like him doesn't mean they are or even will be.
- Teal'C and Ronon Dex filled the same role on two different Stargate shows, the alien ally who had a long, personal history with the enemy and beat people up. A character who was on both shows noticed this and decided they'd work well together. When they met she immediately began to think otherwise.
- When Angelus from Angel gets "I'm not like you" shouted at him by Faith he admits it to be true but then adds "You will be."
- In Fringe the original universe olivia can tell that the alternate version of her is not the same olivia. Peter can as well.
- Harry Potter starts to find the similarities between him and Voldemort fairly early on; both are dark-haired, relatively popular guys who started out their years without parents and found Hogwarts to be their home. However, each circumstance is marred with differences; Voldemort was conceived through a loveless union. His mother, while sympathetic, still gave her son to an orphanage. Voldemort instigates much of the antagonism against people in his youth. Harry on the other hand, had parents who loved each other and mother was brave enough to sacrifice herself against Voldemort.
- To the uniformed, CM Punk and Jeff Hardy's could have been thought to be much alike. Tattooed, skinny(by Wrestler standards) weirdos who both wrestled in ECW. Before their rivalry became serious(before CM cashed money in the bank on Hardy) the two had a civil argument on Raw which ended in Jeff in saying "You know Punk, we're pretty different." As their rivaly became more bitter, these differences became apparent to everyone.
- In Fire Emblem: The Path of Radiance the two hateful jerks you employ sort of stick out for bringing down their more optimistic teammates but at least when they're on a mission together they'll finally have someone agreeable to talk to right? Nope, one of them likes the company but not the job, the other loves the job but barely tolerates who he works with.
Hello, Unknown Troper. You'll need to get known to lend a hand here.