Do you have any pointers about this? As someone on the outside they always seemed two of the same to me except for the kind of equipment they had access to.
There are certainly similarities, since they are both military organizations, but at least in my experience, a couple of key differences are:
(1) The equipment the Navy operates is much more complex, so there is more emphasis on technical expertise in the equipment and less emphasis on the kinds of skills that you need in, say, an infantry unit.
(2) Ships at sea are much more self-contained operations than anything the army does. (This is even more true of submarines, which might be out of communication with the rest of the world for days, weeks, or even months at a time.) This affects the workings of ship crews in many ways: for example, the captain of a ship at sea has more of what might be called absolute power than the commander of an army unit. Also, officers standing watch on ships at sea, particularly at night, have a very grave responsibility that doesn't have any obvious counterpart in peacetime in the army. (One illustration of this is the collisions in the Pacific, which show what happens when those watch officers make mistakes.)
A couple of more things; traditions and cultures are vastly different. The US navy was around long before a standing army. Also there’s a notion of distance to the people pulling the triggers; point of the spear. In the navy and Air Force relatively few people pull triggers, in the army and marine nearly everyone does which leads to the old saying; the marines are a department of the navy, the men’s department.
Their missions are different to clearly. Naval operations center around force projection and protecting aircraft carriers ie aircraft carrier battle groups. The army conducts either low intensity peace keeping or counter insurgency ops or high intensity ops, like countering a soviet invasion of Western Europe during the Cold War ie maneuver and heavy army.
