Not sure either.. This one
http://www.newegg.com/Product/Produc...-355-_-Product is more open and seems to blow the air directly onto the GPU while the other one is more closed but blows the air in a focused beam toward the GPU and let the heat escape out from the back of the GFX.
TBH I don't think there's any difference, if there is, it's most likely nothing more than 1,5C.
EDIT: About the noise level, I think it's pretty much the same for either of the cards.