The book is basically the script for the movie. If you’ve seen it, you’ve read the book. There is no difference. The book goes into a tiny bit of detail but nothing that makes a great difference between it and the movie. The book is more racist. There are two scenes with a Black and Japanese person that didn’t have to be in the book. 

One cool thing is that the actress in the film, Mia Farrow, narrates the book. So I was remembering all the scenes from the movie with her voice narrating. She has a really nice voice and she did a great job.