The Navy is almost never mentioned compared to the Army and Marines where I'm from.
Yea the navy or maritime force isnt much up for discussion or popularity even though sea based war is so big
Agreed, maritime war is so big yet it is really under exaggerated at times. 
Yep the navy is a branch of the armed forces and used for naval battle but isnt much of a thing
So what makes them so different? Do they just train for sea combat and train to use boats instead of other equipment?
The entire strategic point of the navy is to protect the borders and shores of a country
That makes sense, since all borders eventually end up at some form of water, at least continental wise.
-lanes, deter or confront pirates, ferry troops, or attack other navies, ports, or shore installations). The strategic defensive purpose of a navy is to frustrate seaborne projection-of-force by enemies. The strategic task of the navy also may incorporate nuclear deterrence by use of submarine-launched ballistic missiles. Naval operations can be broadly divided between riverine and littoral applications (brown-water navy), open-ocean applications (blue-water navy), and something in between (green-water navy
Joint Expeditionary Force (Maritime)
Joint Expeditionary Force (Maritime) (or JEF (M)) (formerly Response Force Task Group (RFTG)), is the Royal Navy's expeditionary task force maintained at high-readiness and available at short notice to respond to unexpected global events. In addition to the Royal Navy and the Royal Marines, the RFTG also includes elements of the British Army and the Royal Air Force. While it is primarily poised to conduct war-fighting or amphibious operations, the JEF (M