However, it is rather true to the novel, despite its several deviations. Most of the time, there are major changes due to the myriad of reasons why many pieces of fiction do not translate well to film. In this case, most of the changes are minor and hardly noticeable. None of them changes the essence of the story Meyer told.
Warning: There are both movie and book spoilers ahead.
In the Twilight movie, Edward follows Bella to Port Angeles when she goes on a shopping trip with her friends. He does the same in the novel, but the film deviates from this part of the novel in two ways. Firstly, Bella does not enter the bookstore in the novel because it appears hokey and she knows she will not find what she needs there. In the movie, she not only enters the store, but she also buys a book. Furthermore, it is not as hokey as the store in the novel. In the movie, it is a Native American bookstore. The second way the film deviates from this part of the novel is a scene where Edward rescues Bella from a group of men who mean to assault her. In the novel, Edward tells her to get in the car and speeds off. In the Twilight film, Edward gets out of the car and strikes a menacing pose at the men.
After Edward and Bella get together in Port Angeles, Edward drives Bella home. This is true in both the novel and the film. However, this is the time that Bella admits she knows Edward is a vampire and he agrees with her in the Twilight book. In the Twilight movie, Edward does not confess to his nature until the two skip school and take a walk in the woods — which never happens in the book. In the movie, she finds out he sparkles in the sun at that time. In the book, she does not find this out until an entirely different trip to the woods, during which they also have a conversation about his predator nature, which takes place in the school-skipping scene in the film. Oddly, the aforementioned “other” trip to the woods that happens in the book also takes place in the movie; it is just altered. There seems to be no reason for this flip-flop, added scene and moved moment of confession.
This next difference between the Twilight movie and the film has an obvious reason and that is that girls in their underwear sell movies. In the novel, Bella Swan and Edward Cullen have their first kiss after emerging from the much confused forest scene. In the film, it takes place in Bella’s room, after her father is in bed and while Bella is in her underwear and a t-shirt getting ready for bed. That is obviously more theatrical and better for a film adaptation, but nonetheless different from the novel.
In the Twilight movie, Edward Cullen approaches Bella in her driveway and tells her he wants her to go to his house to be formally introduced to his family. In the book, this happens in Bella’s kitchen. Once she makes it to the family home in the film, the Cullens are preparing her an Italian meal. They do no such thing in the book nor are Rosalie and Emmet there, as they are in the film. Furthermore, they do not leave the house during the visit, as they do in film. Bella meets the family and then Edward plays the piano for her. There are no graduation caps on the wall during Bella’s tour of the house, but they are there in the movie.
In the Twilight film, there are hints that Jacob’s father Billy does not approve of Bella’s relationship with Edward. In the book, he confronts her about it in the kitchen at the Swan home. In the film, he does not confront her personally.
Esme, Edward’s mother, is much more a part of the Twilight novel than she is the film. In the novel, she explains to Bella that she tried to kill herself after losing a child. She jumped off a cliff and Carlisle turned her into a vampire to save her life. Bella learns this at the family baseball game. In the movie, Esme does not explain her change to Bella. Another small change in the baseball game scene is Edward and Bella leaving alone. In the book, they are accompanied by Emmett and Alice.
After Bella is on the run from the tracker in the Twilight book, he pretends to kidnap her mother and plays a family video in the background of a phone call and in a trap to make Bella believe her mother is there. In the book, it is a movie of Bella at the beach with her mother. In the movie, it is Bella complaining about how bad she is at ballet.
Another story that is missing from the Twilight film is that of Alice. In the book, the tracker James tells Bella about how he tried to hunt and kill Alice when she was mortal, but that he failed when another vampire changed her. He said that Alice was locked up in a mental asylum at the time. Unfortunately, this is kept out of the film, though other back stories are added to later Twilight saga films.
A few random differences are diner scenes in the film that don’t take place in the book, Bella fainting at the sight of blood in the book, but not in the film, Bella getting ready for the prom at the Cullens, not at home and being tricked into it in the book, but not in the film.
The first of the last two small differences between the Twilight novel and the Twilight film that was obvious to this reader were that Bella was bitten on the hand in the book and on the arm in the film. This could have been so that the scar did not need to be present in every scene. The other difference is that Jacob visited Bella in the prom in the book and in the parking lot in the film.
There are many much smaller differences between the Twilight film and the Twilight novel. However, the majority of them involved pieces of the book that could not translate easily to film, such as the thoughts of characters that reveal things like Charlie’s ability to shield Edward’s power in much the same way as Bella. None of them was entirely necessary to the story.