The book has far more depth, especially in character development and depiction of society's complexity in a small Southern town. The bit parts given to several characters are merely a nod to their major roles in the book, but are done so well that someone who has only seen the movie will derive some small insight from the scene.

To Kill a Mockingbird, book and movie, are both fine works of art in their respective genres. They are connected, but independent of each other. Each was approached as a production of a particular type of art, entirely true to the art's nature and to the story it tells.

The Harry Potter movies, on the other hand, while entertaining, are so obviously creatures of the books that it's hard for them to be enjoyed by people unacquainted with the books. (Besides that, all the fans sit in the audience asking why the movie cut a favorite line from the book, and then proceed to quote it...)

Ender's story could be told in one movie, but it would have to be written as a movie, with a screenwriter's eye as to what parts of the book communicate the story's essence and the courage to leave the rest in the book.

To put Bean's story in the same movie would need a genius screenwriter, though. Bean's point of view is a real eye-opener after immersing one's self in Ender's. I think that switching from one to the other would make me dizzy, or would turn it into just one more third-person-omniscient narration.