COMMISSIONED OFFICER. Commissioned Officers are the managers, problem solvers, key influencers and planners who lead Enlisted Soldiers in all situations. Enlisted Soldiers perform specific job functions and have the knowledge that ensures the success of their unit's current mission within the Army.
The primary difference between chin-ups and pull-ups is that chin-ups are done with a supinated grip, palms facing in toward the exerciser. This sets up the mechanics so that chin-ups, while still primarily a back exercise, also provide a good arm workout, particularly for the biceps.
Your pectoralis minor does do some of the work, as do the biceps, shoulders and other muscles of the back -- but for the most part, the pull-up is a lat exercise. The pectoralis major, the larger of the two pectoral muscles, is not activated much at all by pull-ups.