No, they both have openings for fans. The only difference that I can see is that one has "OEM" in the title and the other doesn't.
OP, sorry but I don't see any difference at all. I read the reviews and they didn't mention any features that one had and not the other. It may be that one of them is painted black and the OEM one is not, but that's pure conjecture.
If I were you, I'd call CM customer service (909-673-9880, 8:30-5:30 Pacific time) and ask them.