Originally posted by: DJFuji
Originally posted by: SirWoj
The Marines are not a branch of the Navy. They are their own service under the Secretary of the Navy. They have their own commanding general who is equal to the commanding generals of the other services. The official name escapes me. Please don't tell a Marine that they are part of the Navy. The Marines are shock troops who work both with and independently of the Navy. Marines are quick to deploy and deal with small wars like Grenada or Haiti. Marine Corps boot camp is more intense and concentrates on shooting, aggressiveness and strict discipline. Every Marine is a rifleman and the Corps follows a strict caste system and set of traditions.
The Army is a very large organization and still stuck in the Cold War era type of fighting. This involves large concentrations of heavy armaments ready to fight the communist threat. This attitude is changing though. There are more opportunities for learning a skill and moving up in rank because the Army is larger. They also offer college benefits through the National Guard. The Army follows a more touchy feely doctrine because they do not follow the cultish warrior ethic that the Marine Corps instills. You would never hear of a Marine Corps of One like the Army of One.
Well those are my interpretations of the Army and Marine Corps. I was in the VT Corps of Cadets for a while so I think I have some credibility. In a nutshell the Marines have loads of espirit de corps, and once a Marine always a Marine. Marines go into harms way very often and celebrate their ability to fight very hard. In turn the Army is a very large organization that is slow to move but offers more opportunities to learn a skill and advance. There is less chance that you will be on the front lines with the Army and also less espirit de corps and loyalty to the branch.
*Sigh*....
This is one of those "is karate or judo better" types of threads...
Anyway, SirWoj, that was a FAIRLY accurate synopsis of the difference. While i'd love to contribute to this thread by thrashing the other services and saying the Marine Corps is the best, that's not what the OP asked. (even though it's still true.

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Now, here's the end-all, solve-all to the question:
Aside from the DOT Coast Goard, there are 4 branches of the Armed Services. They all fulfill different missions and requirements. Keep in mind that the scope of each branch often overlaps with other branches.
Army
The Army is generally the large, land-based infantry service that specializes in occupation of a country and all purpose ground combat. Because of their large size, they move slowly, but pack heavy firepower. They're kind of like tanks compared to motorcycles. Slow, but lots of firepower, even if the guy behind the tank isn't very well trained.
Navy
The Navy specializes in seaborne military power. While they play a more supportive role than the combat-oriented Marine Corps or Army, they nonetheless have lots of firepower behind them. The Navy supports the combat aspects of the Marine Corps by providing transportation and medical personnel.
USAF
The air force, as its name implies, is primarily air-based power. Because they rarely fight in ground combat, their physical standards are not as stringent as the other branches, leading many to poke fun at them. The atmosphere of their service is of a more relaxed nature.
USMC
The Marine Corps is the smallest branch of the armed forces, and is therefore the fastest to move and the most versatile. It has traditionally been considered to be a "department of the Navy" though we do exist as our own service. When asked if the Marine Corps isn't just a department of the Navy, most Marines will respond with, "yes, but we're the men's department".

The size and structure of the USMC can be a good thing and a bad thing. It's good in that we can deploy anywhere in the world within 24 hours. A large force like the army moves too slow for that. It's BAD because we don't get the funding the army or USAF gets. We generally get the leftovers and 2nd hand gear from all of the other services.
It's true that Marines are generally better trained than the other services, but that once again comes down to us being small. It's much easier to be "elite" when you're small. Look at it like a small and large family. It's MUCH easier for a family of 2 parents and 2 kids to have disciplined kids than for a family of 2 parents and 10 kids. As size increases, bureaucracy increases and processes slow down. Movement is hindered and the unit or organization loses mobility. The Marine Corps is almost like a cult to some, and that's very hard to maintain if an organization gets too big. You start to lose traditions.
The other reason for the better training is because the Marine Corps is small and we all have little-man syndrome. Seriously. The Marine Corps only makes up 8% of the Armed Services. The Marine Corps? strength is based on three things: Littleman syndrome, traditions, and a warrior ethos. Marines are trained from day one to be a fighting force. There?s no such thing as ?I?m admin, I don?t fight.? Unlike the other services, the Marine Corps recruits people SPECIFIALLY to fight. If you're in the army, navy, or AF, you may exist in a supporting role and feel that you're not there to fight. In the Marine Corps, EVERYONE is a rifleman first. Whether you're a clerk, mechanic, or webmaster, you're always a Marine Rifleman first.
The Marine Corps? niche is in quick, effective, versatile military operations. Many people think that Marines are ?special forces? because relative to the other services, we play that kind of role. We get in first, get the job done, and get out. We use land, sea, and air power, but lack the raw firepower of the other services. With OIF II we actually shouldn?t be occupying Iraq. That has traditionally been the Army?s job. We don?t have the resources or manpower for sustained military operations in one area.
Special Forces
Now, what are delta force, SEALs, Marine Force Recon, and Rangers? And why are Marine Expeditionary Units called ?Special Operations Capable?? Here?s a synopsis:
Delta Force:
Super secret and elite special forces that falls under the Army. Not a whole lot is known because the Government keeps denying they exist. I?m not sure if they fall under SOCOM
SEALs:
The Navy?s elite special forces. They specialize in basic underwater demolition and other usually sea-based special operations, but like most special forces, they are versatile enough to do most everything.
Marine Force Recon:
Technically not ?Special Forces? as they don?t fall under SOCOM. However, many people consider them SF because they have equivalent training and are the ?cream of the crop? among the USMC. They specialize in reconnaissance, though they?ve recently been deployed to perform various special forces type tasks.
Rangers:
As I understand it, Rangers are the ?super grunts? of the Army. They?re not delta force, but they?re better trained than your standard grunt. Because they?re smaller in size, they can operate more like the Marine Corps. In smaller teams, more effectively, and with more of a ?warrior? ethos.
MEU(SOC):
Marine Expeditionary Units are Special Operations Capable because they have the training, but don?t fall under SOCOM. They are general purpose, forward deployed units that can quickly handle most combat environments.