The lack of sights is the main difference from what I can tell. The gun uses a "sight-channel" concept instead of raised sights. The idea is that it is easier to conceal. They are betting that the gun will be used for close-quarters, point-shooting type scenarios. My choice would be the Defender, or a compact Kimber with sights.
Colt New Agent
The sight channel idea was also used in the Kimber Ultra RCP a couple of years ago. I think it is kind of gimmicky, but can see how it might make it slightly easier to carry (maybe), and the channel would be better than no sights for close-quarters since you could use it as an index while looking over the top of the gun. I personally would rather have a good set of lo-mounts.
The Kimber Ultra RCP