Mark of chaos's campaign was linear (you don't get to choose anything pretty much, just battle after battle). Total war will at least give us the ability to build armies to defend altdorf from orc hordes, or perhaps find ourselves ambushed by beastmen in the hochland forest, and I'm sure they'll be some kind of naval thingy so we can have landing parties and some kind of warhammer naval battles.
I also forsee Tilean/estalian mercenary units for hire, some kind of tech tree where we unlock cannons, helblasters, better handguns, etc.
Also, completely new to TW will be characters. Hopefully they will give us the ability to have customized characters that either shoot fireballs or swing runefangs or pray to sigmar for us.
Mark of chaos just sucked because of the cruddy campaign, the lack of a significant multilayer community, and gameplay that was EXTREMELY brief and clunky. The AI would just charge headlong at you and clobber your units to bits before you could do any tactical manueveres. Also, there was literally no time to cast all of your spells and abilities so you ended up just watching helplessly as the two armies clashed.
TW has never been like that before, even with Rome 2.