Is there any difference between iphones from different carriers?

Is there any difference from say a sprint iphone and a verizon iphone? Could you activate a iphone that supposedly says it is for one carrier with another company or can they actually only be activated with the carrier that they say? Also since sprint owns virgin mobile and virgin mobile supports iphones, could you activate a sprint iphone with virgin mobile?

I can answer one of your questions, the sprint iphone will only work with sprint not virgin mobile. Only the Virgin mobile iphone will work with virgin mobile.