Right now only the Sith Warriors two Advanced Classes have been revealed, one being a beefed up tank and the other a more agile DPS’er.
The Juggernaut transforms your Sith Warrior into a real tough, damage-shrugging tank class for you to really get stuck it on the front line. These will feature body modifications like that of Darth Vader.
The Marauder favours his rage and channelling it to increase the damage he dishes out, and are far less stocky to give them an agile edge - think Darth Maul and his double-bladed lightsaber, jumping around the place.
Choosing these Advanced Classes is purely a gameplay decision and not one that’s tied to any story progression as all of them will share the same narrative as the core class. Each has two specialised branches of skills to invest in, with a third shared by both.
Think of them as World of Warcraft’s talent specialisation. So far only the Sith Warrior’s two Advanced Classes have been named so there are 14 more to unveil yet. Has BioWare and LucasArts got you excited for this Star Wars MMO?