The Radeon Mac Edition has a 166MHz clock, is available in AGP flavor, and looks to have better refresh rates.
http://www.ati.com/products/radeon/radeonmacedition/specs.html
The Radeon 7000 Mac Edition is available in PCI only. I can't find anything on it's clock.
http://www.ati.com/products/radeon7000/radeon7000me/specs.html
Consider this:
"The Radeon 7000 differs in interesting ways from the 2001 Radeon. While it boasts a faster clock speed and dual-head capabilities, the card has been pared down with one less rendering pipeline and no Charisma Engine to perform Transform, Clipping, and Lighting (TCL) instructions. While these features are used in relatively few games on the Mac (or even the PC), those who like running their titles in 1600x1200 will want to read through the rest of the review closely to see how the FPS scores pan out. The Radeon 7000 isnt necessarily targeted at hardcore gamers though, and --excluding a few nagging issues-- the $50 price drop from the 2001 Radeon will certainly increase its appeal across the board."
and "As a primary gaming card, you wont be able to push as many FPS out of it as you would with the 2001 Radeon, but the $50 price difference and ability to run two monitors will likely be more important to many people."
from:
http://www.insidemacgames.com/reviews/view.php?ID=232
So, like most video card comparisons, it kinda depends on what you want to use the card for.