There's a little dent or wrinkle just above the left knee on both versions, which leads me to think that the legs are the same. I agree with Anton--the different paint apps (and the way the '99 version is posed in both photos) make it difficult to tell, but it looks to me that it's just a straight repaint of the '99 Vader.
The one thing i'm curious about is - the '99 Vader had the lightsaber hilt sculpted onto the left hip, and it's impossible to tell if that's the case with the new Vader, too (at least for me, anyway).