Is there any hardware difference in iPhones from different carriers?

I'm looking at screen replacements for iPhone 4s, and some will be sold as "verizon iPhone screen assembly" and "sprint iPhone screen assembly" and "AT&T iPhone screen assembly." is there anything different? Or is this just a scam to get more money?

IPhones are made by apple and they are identical to all carriers. The only differences are the sim cards as each carrier puts one in to sync to their service only.

Apple does not allow anyone to make their devices different, if they tried they would sue their butts off as it would go against their patents.