Just taking a look at the specs..
Monitor:
Display
27-inch (diagonal viewable image size) thin film transistor (TFT) active-matrix liquid crystal display with in-plane switching (IPS).
Supported resolutions: 2560 by 1440 pixels, 1920 by 1080 pixels, 1280 by 720 pixels
Colors (maximum): 16.7 million
Aspect ratio: 16:9
Viewing angle: 178° horizontal; 178° vertical
Brightness (typical): 375 cd/m2
Contrast ratio (typical): 1000:1
Response time (typical): 12 ms
iMac:
27-inch iMac boasts even greater resolution of 2560-by-1440. That’s a whopping 78 percent more pixels than the 21.5-inch model. And more pixels mean images look crisp and true to life. A 1000:1 contrast ratio gives you more vibrant colors and blacker blacks. All in a 16:9 aspect ratio — the same as an HDTV...
The iMac display looks great from any seat in the house, thanks to a premium display technology called in-plane switching (IPS). IPS gives you a bright picture with excellent color — even if you’re viewing the display from the side.
While not stated in text, the graphic on the iMac indicates the same 178º viewing angle. This would lead me to believe that they're the same base panel. From a manufacturing standpoint this would also make sense.
So, while I'm making an assumption here.. I believe they are.