What's with the GeForce 600 series boost clocks?

It's normal for different companies and models to have different stock clocks. Often it just an overclock flashed to bios so it defaults higher , for appearance and for non-overclockers. Sometimes a specific model or series will acutally have better limits because of the parts. As for the lottery, no, the specs of what you receive should be the same as what you order, so just reading the listing.