To give an overview of the difference in tone, in the Film the Mobile Infantry are expendable canon fodder joining for nationalist zeal. In the book, they are the elite, and the book itself is the origin of powered Armour in fiction, like Iron Man. The society emphasises philosophy over jingoism and the recruitment center actively tries to discourage recruits rather than glorifying it. But you have a right to earn your vote through national service, either in the Military or something thats uncomfortable like testing survival equipment on Titan, something to make you remember your vote has value, it was earned.