Well they should at least mention the ns ratings, 5.5ns is 183MHz, 5 is 200MHz.
http://www.leadtek.com/3d.htm
From the Leadtek website,
"Enhanced WinFast GeForce2 Pro 32/64MB
The New Enhanced WinFast GeForce2 Pro 32/64MB is the only one in it's class to use 5.5ns DDR memory. Nvidia GeForce2 Pro
64MB 5.5ns DDR memory
AGP 4x (w/Fast Writes)
Hardware Sensors and diagnostic LEDs
Leadtek's unique active cooling module
Original WinFast GeForce2 Pro
The WinFast GeForce2 Pro with 64MB 5ns DDR memory is running at standard 200/400 Mhz (Core/memory) speed. That translated to about 20% performance increase over the original GeForce2 GTS Nvidia GeForce2 Pro
64MB 5ns DDR SDRAM
TV-out
Leadtek WinFox System Utility "
Unfortunatly they dont list product numbers to check for, but I suppose the difference is negligible between them. Meaning the "new" Pro with 5.5ns memory should be able to hit 200/200 anyway, but that also means the "old" Pro with 5ns memory can probably hit 200/230, or close to it, which are Ultra/GeForce3 specs.
Advantages over a Voodoo5 wont be too great, but worth it in my opinion.