Certain classes have different weapons setups, the Republic and CIS Assault differ greatly. The Republic assault has the standard Assault class weapons while the CIS Assault is a Super Battle Droid. Classes are balanced though.
Soldier - Medium Range, Anti-Infantry, Anti-Vehicle
Heavy - Anti-Vehicle
Sniper - Long Range Recon and Anti-Infantry
Pilot - Maintaining vehicles
Assault - Close Range, Anti-Vehicle
6 PTU Special (Jet Trooper, Droideka, Dark Trooper, Wookiee Warrior)
8 PTU Custom
12 PTU Officer - Support (Clone Commander, Droid Commander, Imperial Officer, SpecForce General)
20 PTU Unlockable (Clone Commando, Magnaguard, Incinerator Trooper, Bothan Spy)