... but it's important to remember that the movie version is just an interpretation of the book. It's like when two different artists sing 'Jingle Bells'. Jingle Bells is a very old song with definite lyrics, but the artists give it whatever variations they want.
The Kite Runner is the story of Amir, a Sunni Muslim, who struggles to find his place in the world because of the aftereffects and fallout from a series of traumatic childhood events. An adult Amir opens the novel in the present-day United States with a vague reference to one of these events, and then the novel flashes back to Amir's childhood in Afghanistan.