In the movie American Sniper, there's this Sniper that is in charge of the army squad. His objective is to look out for people up above and snipe them down before any of his other troops get shot
at or killed. In the opening scene, sniper Chris Kyle (Bradley Cooper) is faced with a tough decision on whether to take the shot at a child or not. As the audience is about to learn the decision he made, the scene cuts to Kyle as a young boy hunting with his dad and killing a deer. This scene could be seen as a dramatic cut scene to build tension, however, some have seen this as though Eastwood is comparing killing a Muslim to hunting deer. Bill Chambers, says that the point of the scene was to point out to the viewer that they are hunting animals.
American Sniper is a fictionalized movie version of the war stories associated with Chris Kyle’s experience as a Navy SEAL in the Iraq War as recounted in his best-selling memoir. The film can be viewed from a variety of angles, including even as one more indictment of war as hell. A second line of interpretation focuses on the intense psychological tensions experienced by this single American soldier and his comrades caught up in the horrors of urban warfare in Iraq. A connected theme are the adverse impacts of Kyle’s war service on his family that is made to cope with the complex and contradictory traumas of his absence (confronting his potential death on a distant battlefield) and his alienated presence whenever he returns, a scarred individual who longs to go back to Iraq to resume his assigned role as ‘legendary sniper.
To conclude, the movie and the book, they each have their own story line but they also have two different themes in a way. They run along the same lines but its a little different and up above should be able to explain to you.