Some of the models are the actually the same camera, but sold via different retailers, ixus 125 vs ixus 127 for example? The shops that stock the 'exclusive' model with free case.
My Powershot SX was the exact same as the model up but without GPS. It lives in my glovebox. I'm probably going to buy a very cheap original rebel for my holidays this year, as the compacts just don't cut it. Don't want to take anything worth more than £250 as thats my upper holiday insurance limit.