Alt Clone Wars - Soldier Classifications

These are the types of soldiers in the clone army (phase 1)

Assault - Basic soldiers of the GAR
Heavy - deals with heavy weaponry, such as sentry guns
Sharpshooter - sniper
Officer - officers are every soldier above the rank of private. Officers do not actually have a standard issue set of armor as they are allowed to customize their armor. 
Gunner - operates heavy weaponry on ships and vehicles
Driver - drives all ground vehicles
Pilot - pilots starfighters and gunships
Aerial Specialist - equipped with jetpack for quick mobility and bombardment from above  
Advanced Recon Commando - you know what an ARC trooper is
Commando - used for more discreet purposes, such as sabotage and stealth missions
Airborne - basically a paratrooper, often dropped behind enemy lines
Advanced Recon Force Trooper - highly trained in survival methods and often used during battles where supply was difficult to get
Light Armor Mobility Trooper - a less armored clone, mostly used in hard to navigate terrain (swamps, rocky mountains, etc.)

This list does not include weather/climate specific soldiers, such as snow troopers, SCUBA Troopers, or Jungle troopers.

Credit to elMengu MarcusStarkiller MiddytheKnight