I would strongly recommend you take the time to thoroughly read through the XDA forums before embarking on such endeavors in the future. Too many half-assed tutorials with loads of misinformation floating around. The S3 is an extremely popular device with a huge developer following. If you take the time to read through the developer forums and even the Question and Answer forums on XDA, nearly all of this would have been avoidable and you also wouldn't have had to endure that sinking feeling in your stomach when you thought you had bricked your phone
International S3 (I9300)
AT&T, Rogers, Bell, Telus S3 (I747)
Sprint S3 (L710)
Verizon S3 (I535)
T-Mobile, Wind, Mobilicity S3 (T999)
Yes, there are differences.