Well heres what I've found out from playing the Demo:

New Civilisations:
Sioux
Aztecs
Iriquios

unique from european sides, the Iriquios are very different, can't play as the other two.

Petards and Horse Artillery:
New Euro units, petards are suicide bombers, Horse artillery are light cannon.

Saloon:
Hire mercenaries in-game, a random two merc units, and two of either bandit on horse (forgot names XD), bandit on foot, or pirate.

Revolution:
A new feature for Euro sides, all of your settlers turn into 'Colonial Militia' and you can buy no more villagers, only colonial militia at your town centre for 100 food a peice, you get 4 cards, none of your own cards, all of which can be sent infinate times, A fort wagon, some wierd steam boat thingies, 16 colonial militia and gatling guns.

Warcheif: Instead of an explorer, the Native sides get Warcheifs, which give aura-type bonus' to allied units.
A few other things I can't think of at the moment.