Shaiya is a very good online game which allows you to choose between the light and dark alliances with different races.
The two alliances have different races but once you pick an alliance, you can't change back unless you delete all of your characters, so your better off choosing light or dark and sticking with it. Light has humans and elves while dark has vails and death eaters. You can't team up with the opposite to your own, so if you have a friend whose the opposite to you, teaming up with them would b impossible. There isn't really a difference to the two sides except possibly quests and monsters. Both sides have a goddess who gives blessing, which are like buffs for the alliance, not just one character.
I enjoy Shaiya but I would like another server on the game because it seems to be always busy so it's only a matter of time before you disconnect from the game. The choice of difficulty at first only gives you easy and normal, easy being the worst because once you reach level 30, you can't learn anymore skills. On normal mode you can unlock the other two modes when you reach a high level.