One of the biggest differences is that the book is written from Bella's thoughts; it is really she who narrates the situations she is in. The reader gets to be Bella in a way and you find out everything she thinks and feels about Edward. Although in the movie reflects on both Bella and Edward, by watching the movie you don’t get the same feeling as in the book. If there are some private thoughts of Bella that the viewer must know about, you get them in the context of the story; it feels almost like Bella is writing a diary.
Another important difference is how Bella finds out that Edward is a vampire. In the book, the school they are going in is having a dance and because Bella is not really that in to dancing she and Edward decide to go to Seattle, but the don’t even go to Seattle instead Edward takes Bella to the meadow and tells her what he is and he reveals himself in the sunlight so that she can see that he is sparkling in the sunlight. In the movie they are in front of their school preparing to go to class and Edward decides to go to the nearby forest, Bella went after him and she confessed that she knows what he is, Edward was surprised and he tries to scare her by showing himself in to the sunlight so that she can see that he is sparkling.
However the book and the movie have a lot of similarities as well. The family dynamics are described very well. In the book Bella’s mother Rene is very eccentric and she cares a lot about Bella, even though she does not get more than a few minutes in the movie, you can easily see her