Most of the songs sound like things Charlie and Kadee would've actually wrote, whether it's minor details in the lyrics (Charlie proclaiming in "Someday" that he'll be "king of the Palace", the name of his family's restaurant) or highly reflective of their mindset ("Not So Different At All" essentially being a song Charlie wrote about himself and Kadee). Even "Nothing Gets Better Than This", which is sung in a Big-Lipped Alligator Moment, is more or less about how Charlie doesn't want to go home and finds comfort and enjoyment in the Pawn Shop.
In contrast, the songs characters are forced to sing have nothing to do with them; Kadee despises "Love You, Hate You" and Android is pretty much just a cover-band, with none of the artistic meaning behind the music and being purely manufactured for popularity's sake — showing how Kadee's father doesn't understand her, and how Arthur is cheap and uninterested in actual creativity. Similarly, Arthur sold Charlie's mother's piano and purchased a karaoke machine — another symbol of him prioritizing pre-written and already-popular music over artistic integrity.
Throughout the film, we see Lloyd get treated as though he's a terrible dancer who is holding Andrew back. This can make it seem strange when he manages to keep up perfectly during the much more complicated dances at the masquerade ball and at the very end of the movie. A closer watch reveals, however, that Lloyd was always the one with more talent, being less stiff while dancing and a decent beat-boxer as well. This all adds up to the fact that Andrew and Arthur, being jerks, adopted a Never My Fault attitude and took to blaming him regardless of how talented he actually was. In cases where he could dance without their influence, he thrives.
During the performance of "Not So Different At All", Kadee is visibly impressed, which is fitting because the song is about herself and Charlie, even if she doesn't realize it. However, another character who's impressed is Lloyd, who is also "not so different" from Charlie — they both suffer from the same Abusive Parent, both have the same ambition, and both get pushed around and mocked constantly. It only makes sense for Lloyd to be just as interested in the song — he can relate to it as well, especially when realizing that Charlie's the singer!
