A few months ago I made a post, asking about the difference between PVD OP6500 and OP6502 case
So I had a chance to compare both side by side
I had a PAM9A and a PreA9 OP6500 case for comparison
Probably some of you might already have know the difference but let me show you the difference once again
So here's the 9A
Here's the PreA9
Here's the 2 side by side:
At a glance the most obvious difference we can spot immediately is the crown guard pin, the 6500 CG pin is not PVD finished, so it appears silver in color, while the one on the 6502 case is all PVD finished 

I'm not sure if I took the picture nicely to be able to show the difference, but if you can notice, the 6502 has more of a matte black PVD color, while under the sunlight, it appears a bit of gunmetal color. While on the 6502 case, it's more of a lead pencil gray color but appears a little bit bluish/purplish under sunlight

So here's the side by side profile shot
the 6500 is basically a PreV case, so we can see that the lugs is exactly in the shape of the PreV case lugs... A bit beefier and appear thick, squarish on the bottom... While the 6502 appears more elongated (at least in shape)
Hope this is useful
Best,
Sam
This message has been edited by samrotandi on 2011-09-18 17:25:05