Their units are different, with the superior Roman technology, while the Gauls depend on their numbers. There is a third, non-playable faction, the Teutons, a nomadic people who live in tents throughout the map.
The Roman and Gaul units differ in terms of technology, whereas the Gauls rely on sheer numbers. The Teutons, a nomadic group, inhabit tents across the map, forming a distinct faction.