When there's diversity, there's variety. Often, this word is used for diversity of race, class, or gender.
To have diversity, you need a mix of whatever you're talking about. If you like science fiction, romantic comedies, cartoons, and action movies, then you like a diversity of types of films. If you like nothing but kung fu films, then you don't like a diversity of films. No matter what kind of diversity you're talking about, there needs to be a real mix, kind of like a huge box of Crayolas.