In the The Hobbit: Kingdoms of Middle-earth you are prompted to chose from two playable races when you first begin the game, these being either the Elves or the Dwarves. The choice of race doesn't provide any advantage either side, both races have the same buildings, mechanics, research, troops etc. The difference is the visual appearance and naming of such things.
Typical battle troops are trained in a barracks, they continuously require food upkeep to be maintained when they're in your city, however defense troops trained from City Wall cost no food upkeep. The defense troops are not able to be sent into battle and can only defend the city, where battle troops are able to both attack and defend.
For both races there are four types of troops; foot, ranged, mounted and supply. Each having an advantage against one type of troop and a disadvantage against another (except supply troops, which are used primarily to transport resources).
There are five tiers of battle troops which can battle, however currently only the first three tiers can be trained, the other two remain for in-game contests. The attack, health, speed and carry load of troops increases depending on the tier it belongs to. However, more resource and higher building and research levels are required to build stronger troops.
The guardians of Mithlond, the Grey Havens, are among the most heavily-armed Elven troops. Unprotected by moutain or forest, the port city depends upon its guards to defend it.