What is the difference??

I just got the Gainward TI 4200 from NewEgg and was wondering what the difference is between it and the Chaintech TI 4600.
It seems to overclock well,got 10455 out of 3D Marks,but I was contemplating getting the TI 4600 also..
Thanks

Chaintech has 2.8ns RAM and VIVO. I am unsure of there OC ability, but you have a nice card already.