Each of the services have many different cultures, each centered around a particular function. In the navy the main divisions are aviation (the carriers), submarines and surface warships. The differences here are striking. The aviators see themselves as the naval elite. Part of this is riding on the stunning World War II naval victories won largely with carrier aircraft. But this admirable legacy is supported by the continued use of naval aviation to get there first with the most (or at least something) in a world full of little wars and unanticipated crises. Within the navy, the submariners see themselves as the true elite. For one thing, it's more difficult to qualify for submarine duty than for naval aviation. Then there is the fact that the what American carriers fear the most is submarines. When the nuclear sub appeared in the 1950s, it was generally acknowledged that this was the new top dog of naval warfare. But two things deny the submariners their place of honor. First, their superiority is largely theoretical, especially to the public. Nuclear subs have been used in combat only once, during the 1982 Falklands war when a British sub sank a World War II era Argentinean light cruiser. Untried in combat, subs can only get so far on potential. Second, subs spend most of their time out of sight, under water. And when they are on the surface, they don't look all that impressive. Image is important, and the submarines don't have a very striking one. This, however, leaves the surface warships looking rather shabby compared to the aviators and submariners. Indeed, submariners tend to refer to surface vessels as "targets" rather than ships. Moreover, with all the prestige attached to subs and naval aviation, the surface ships get the leftovers when it comes to personnel, and other goodies. This stature race is not inconsequential, for the branch with the higher profile and prestige tends to get more money for new stuff.
The budget rivalry between branches is common in all the services. In the army, armor, artillery, infantry, aviation, intelligence, signal, engineers and the other branches constantly struggle for bigger shares of the budget. This strife often becomes counterproductive, for the money doesn't always go where it's needed the most. The most striking example of this is seen in the way Congress is attracted to defense spending programs. The politicians favor large, expensive gadgets. Thus most of the procurement money goes to sexy items like helicopters, tanks and complex armored artillery systems. Meanwhile, the infantry, which takes the most casualties and ultimately decides victory, gets left behind. The infantry needs new equipment, but their needs aren't nearly as glamorous. New boots, rucksacks, portable rocket launchers and the like get little attention, even those these things mean much to the grunts. The current black hole for infantry procurement money is an elaborate, science fiction like ensemble that the troops are leery of such complex and high tech endeavors. But it took something striking to attract money. This is no trivial matter, with post Cold War warfare more dependent on fighting irregulars in urban areas. Want to take a city or urban area? You need infantry to do it. And most of the things worth fighting for are found in places with lots of buildings. Tanks die in cities and artillery throws blind punches. Only the grunts can go in and take possession. But facts like that don't count for much when it comes time to spend money. The infantry get a lot of lip service, but not much cash.
The situation is different in the air force, where the only combat troops, the pilots, are lavishly serviced with attention and money. As one might expect, the air force has several different pilot "unions." The fighter pilots are the top dogs, with the bomber crew coming up right behind. Again, post Cold War realities demand different priorities. All those far off little wars require transports, and the "truck drivers" that pilot those aircraft are barely tolerated by the combat fliers. The air force also provides some interesting comparisons with the large aviation community in the navy. The carrier pilots consider themselves superior to their air force counterparts. There's some truth to that, as landing a jet on a carrier, especially at night, is the most difficult task a pilot can face. Partly because of that, naval aviation selects and promotes its pilots by constantly challenging them. This is hard to avoid, given the challenging nature of carrier flying. The air force is more systematic, feeling that, given enough training, they can produce the needed skills. Neither approach has a clear cut superiority, and both are practical adaptations to the different environments.
The many different military cultures account for the good, and bad, things that happen to the troops.
Cultures; People in the military are different. More interesting are the differences between various types of troops, even those who appear to do the same job. Take infantry. The army and marines both have thousands of men trained for ground combat. But the two services go about their jobs quite differently. Many of the differences are minor. The uniforms are similar, but different in small ways. Some of their weapons are different. Even the way the two flavors of grunts talk to each other. Army troops say "yes sir" when talking to an officer, while a marine is more likely to say, "aye, aye, sir." But if you go from an army infantry platoon to a similar unit of marines you will quickly notice a difference in attitude. It's a difference you sense, but a difference you know is real. But the marines are one of the more obviously unique military cultures. There are many others.