DarkFall is different in the sense that there are no levels. That's right, no more grinding to get to the next level. It's all skill based. Skills increase as you use them you can learn almost every single skill except for a few race-specific ones. There is a skill cap, and it is at 100 for the moment.
The World
DarkFall takes place in a huge world, possibly the largest single online world ever created. You can gather your clan and build cities! Or get a small shop and be a merchant! Or be a pirate and find a small island to set up your secret base! The options are endless! You can be anything in the world of DarkFall. There will be no zones, no zone loading and only a short loading pause when entering dungeons or buildings. Spawns in the game are dynamic. Clear out a spawn and it will not reappear in the same place. If you spend enough time killing a species, its presence in that area will thin out and eventually the species will migrate to a different area. The player can control the amount of gore in the game. With a no gore setting you will have no gore whatsoever, whereas with full options you could watch a perfectly timed and powerful swing of a sword take someone's head clean off their shoulders.
GamePlay
There are no safe zones in DarkFall, meaning that you can be attacked by anyone, anywhere. Calling it a PvP centric game wouldn't be enough. Think large clans. Epic battles. Kingdom building. It's all that. Combat is like Oblivion with first person and third person views. Casting spells takes a shorter time in robes than in armor. (E.g. A spell that takes 2 seconds to cast in robes would take 4 or more seconds in full plate) There will be horses and other mounts to mount, ships to said and magical means of transportation around the world. There is also mounted combat. Currently there are six races. The Humans, the Alfar, the Dwarves, the Mahirim, the Mirdain and the Orks.
The game would be focused mostly on clan warfare and kingdom building, with dynamic economies and the like. Of course, you can be a lone wolf, going around on your own, trading goods or assassinating people. Like I said earlier, the options are endless.
Conclusion
There are lots more about the game to read about at its site,
where you can read about its features and lore. There is also a video that compiled a whole bunch of gameplay footage into one video. Most credit goes to the DarkFall team, which created the game and FAQ from which I got most of my information. The rest goes to everyone else that posted information on the game.