its just a dl. its specified as such because snatch dl's are also called in the wods.
there was a discussion of this back in october. check out the comments for:
Clean deadlift is what most would simply call a deadlift, which uses a clean-ish grip normally. It's specified here because we're also doing snatch DLs.
The key point to keep in mind though is that we're trying to strengthen in the correct positions and movements - so if when you deadlift normally you, for example, shoot your hips up immediately and back lift, you need to break this habit and pull the DL exactly as you would a clean or snatch off the floor. That is, set the starting position correctly and bring the hips and shoulders up at the same rate. Any strength work we do is always ALSO positioning/technique work.
If your clean is considerably lower than your DL like that, take the DL up to what feels to you like a heavy triple--you'll just need to make adjustments like this until your Oly technique catches up a bit more to your strength.
— Greg Everett | 2007-10-08