The 902 is a superior case,the materials used and construction is better.
It weighs 10lbs more.
The drive bays are removeable,not fixed,its interior is finished.
All the fans are TriCools.
I'll venture to guess it's quieter also, and has better cable management.
The price difference is only $40 if you go by Newegg's regular pricing.
I looked at the 600 when i bought my 902.