While I really enjoyed finding the two variations listed in previous messages, because they're tougher to find than significant back differences or different manufacturer markings, this one may be my favorite. Before finding this, if you had asked me if I had the variations of the gold Paiza keys, I would have said "yes" thinking, "well, I have the one that says Las Vegas at the bottom and the other one that says The Venetian Las Vegas". Finding this one reminded me that you never know how many varieties are out there of any given key. Enjoy!

Yes, there are some shading variations between the keys, but that's not the most significant difference. Once again, the hint is to look at the back. A second hint is that little ruler I've added to the scan of the backs