There's at least the clock-speed difference...You have to factor in AMD insists on making their cards much more potent at FP32, which hurts their energy efficiency something fierce. Because of this, we don't really know how far behind GloFo's efficiency on their 14nm node is... but it still seems to be worse than TSMC's 16nm for certain.
But here's the thing. It's obviously cheaper per mm, or AMD wouldn't be selling these cards for so cheap. That's part of the nice thing here when it comes to what AMD offers, is it shows something really interesting about what GloFo offers. But that's something that belongs in an entirely different thread. I'm kind of happy both with AMD and GloFo at this point. What that means in the long run is where the money is.