@anon_opin easy dividing line:
fancy-dress is "this kinda thing"
cosplay is "my costume is correct, as per the scene between these two characters which has 0.3s of screentime in the region/language-specific version of the film/episode/cartoon shown once at 4am on a Sunday. that is why my sock is that exact shade of pink, not because of a laundry accident. you know nothing!"