http://starwars.wikia.com/wiki/Star_Wars:_The_Force_Awakens_(novel)

The novelization is the same as the movie but since it's written out, there are certain things implied in the film that are right there in black and white in the book.

It's not that you need to read the book or that they are putting different stuff in the book, but some of the hints and clues as to what is happening and some of the motivation behind what is happening is given background in the book.

Specifically in this case, when watching the film it felt like Rey was using some of the dark side during that fight, and the novelization confirms that feeling.