Neither of them are what you could call original, but UT is just, well, better. Of course you do, so I am going to tell you. For starters, Epic Games have come up with six different modes of play. CTF, last man standing, domination and assault. The two latter are brand new to this type of game.
Domination consists of two to four teams trying to take control of three areas of the map.
Every second that you have control of one area you get one point. The team that manages to get the set number of points first wins. Assault consists of linear missions that must be completed in the time limit. There is a defensive team and an attacking team. That's a lot of gameplay.