I have both and I can tell you the 480 is way better for games. I purchased the 560ti first, then saw on newegg the 480 for about $210.
After installing I ran the ff14 benchmark test and the scores were something like the 560ti ~4200 and the 480 was ~ 7000.
The 480 has a better memory bandwidth which probably helped. My gut tells me that it would be better for 480. As Mactronix says, make sure you have the power.