well the superclocked version has a higher factory clock (was OCd by evga) and the other wasnt. but there is another difference in your case. you have a SC 1GB model, and a non SC 2GB model, and this is the real difference between the cards.
if i were you, id go for the 2GB model, as you can always OC it yourself if you wanted, but you cant give the card more ram.
if youre interested in a factory OC, there is also a 2GB SC variant from EVGA available.