as long as both devices are purchased unlocked at the apple store, they are identical.
if you buy them from the carriers stores , even full price, they are sold locked, but they are also identical
the only difference between iPhones is the serial numbers, each iPhone is on a list and its that list that dictates if the iPhone is an AT&T phone, a t-mobile iPhone or a verizon model.
the sprint model is the only one that is different