There have been so many movies that have been adapted by the books. The most famous one The Harry potter, but in the movies there were a few changes that were done. The adaptation of the movies are always changed to suit the timings and the climax.
Like the book Fallen, the protagonist was seen as different but in the movie, she was not portrayed as such. Their romance in the books was slow and took time but in the movie, it had to be fast as movies are usually to 2-3 hours.
Even the shadowhunter books by Cassandra Clare, the fights and the conclusion was shown differently, while in the movies it was fast paced and the plot could not be shown as much as the novel.
The Dan Brown books has also been adapted as movies, but it was good adaptation. As the viewers can understand the plot well and the professor goes on many journey to solve the mystery with the help of someone, like the da Vinci code, angels and demons and Inferno.
Essentially, books have more information and they have time to deliver it, but movies are more fast paced and they skip little tidbits of information.