[Build Help] Quick question about the XFX 6870

Hey guys, I'm finally, finally, finally in a financial position to put together my first rig. Super excited about it, but had a quick question about the XFX 6870 if anyone can shed some light. There are two versions of this card: here and here.

I'm having a hard time telling if there's any real difference between the two other than one has two fans and is longer and the other has one fan and is, of course, shorter. Does either have any advantage, or is it entirely about the amount of space they take up? Any feedback is greatly appreciated! Thanks in advance.