In the future society is divided into 5 factions. Abnegation the selfless, Dauntless the brave, Erudite the intelligent, Candor the honest, and Amity the peaceful. When teenagers reach the age of 16, they must choose to either stay in their faction they were born from or they can have it chosen for them by taking a test, but what happens if it doesn't just choose one for you?
Tris Prior is a 16 year old who lives in a time in the future where society is divided into five factions. As each reaches a certain age, he or she must choose a faction and conform to it for the rest of your life . Tris chooses Dauntless -- those who show bravery above all else. Tris becoming a Dauntless leads to the discovery that she is a Divergent and will never be able to fit into just one faction. Tris is told that she must keep it a secret, Tris starts a war between her and her enemies that puts everyone she loves in danger.
The Divergent book is different from the movie because there is a lot more details in the movie and more things get explained than in the movie. There is also more backstory to each character. In the book you have more information to what each character is doing at the time but in the movie you don't always know which character is bad or good and what they are doing.
I would prefer to watch the movie than read the book because it is less time consuming, and is much easier. It is also a better experience when you can see what is happening and what each person looks like so its easier to picture.