Well one is the "Extreme" version, which in Asus' world usually means its slower than the normal version (Their X800XL comes with 700mhz DDR1?).
I think the only real difference between those two is the HSF on the card, and even though the pic on Newegg shows the standard nVidia one, I believe that Asus might have switched it over to their own. Thats what several companies did, is when the cards were newer and in limited quantities just used the reference cooler, but then some of them changed them later.