They appear to be different parts (iPad 2 digitizer, iPad 3 digitizer).

That said, I've scrutinized the photos from the iFixit teardowns of both the iPad 2 and iPad 3, and darned if I can see any significant differences. The metal shield around the camera appears to have grown a spring-contact on the iPad 3 to improve contact with whatever it touches, but that looks like it. And it would be very in keeping for Apple to use the same part for both iPad 2 and 3 if they function the same way. The logic boards of each of the two even have their various connectors to the screen and speaker arrays in the same spot.

So: inconclusive. Maybe we'll luck out and an iFixit staffer will compare and contrast the parts for us.