OP, look at it like this. We know for sure that they both have the exact same drivers (as both have identical spec of sensitivity, impedance and freq response). And we know from pictures that physically they are exactly the same form factor, thus you can easily conclude that they are the same headphone and will sound the same...
The chaps at headroom seem to think they are slightly different though, they say that the Q701 just has a smoother treble, otherwise identical to the k701. I personally think they are either saying this just for business, or they are just hearing what they want to hear, but who knows, maybe it is true.
http://www.headphone.com/headphones/akg-q701-quincy-jones.php
Click on the "what we think" tab to see what headroom have to say.