The S3 has a completely different grade of aluminum machining. Maybe meaningless in the long run but the fins are going to be a tad bid quieter.

I should mention these puppies take 4amp fans on both sides if you want to run them wide open. Ive moved it into my house for the evening and turned it down aggressively so it's hashing around 5.5 with antminer fans turned to 30%

Sorry for being a n00b but how do I put nice high res pictures on here ?