There are four branches of the Military, some examples of what each branch has to offer.
US Army (Infantry, Rangers, Green Berets, Delta Force)
US Marine Corps (Infantry, Force Recon)
US Airforce (Pilots, technicians, chair people, Pararescue, Combat Air Controllers)
US Navy (Sailors, technicians, pilots, sea bees, seals)
The US army and USMC both use the M1A1 and M1A2 Abrams series of tanks, however each branch uses them differently. The Army also has armored vehicles like the M2/M3 Bradley, the Stryker, AMPV. The USMC uses vehicles like the LAV-25, the AAVP7. Both branches operate towed artillery systems and mobile systems like the M270 and M109. The USMC has access to some aircraft like the Harrier, the F-18, soon to be F-35, CH-46, AH-1Z Viper, and the Osprey. The Army operates some aircraft like the AH-64 Apache, UH-60, and CH-47.
The airforce operates aircraft like the F-16, F-15, F-22, A-10, soon to be F-35, all the bombers. The operate from airbases on land. The navy operates from carriers and aircraft like the F-18, F-35, and certain variants of the A-6.
