TNT2 M64 vs TNT2 VANTA

I’ve been looking for a cheap video card with good opengl support. On pricewatch I found the vanta for about $35 dollars. After looking into things further, I came across the m64, which utilizes the same 64 bit memory architecture. Many sites list the two as the same product, just a different name. But some other sites also make them seem different (clock speed and memory combinations–vanta only in 8 and 16MB configs, while m64 in 16-32MB configs)
Any good summary of what these are would help. thanks

Helo, I have the riva TNT2 M64 and the results for my computer, has a satisfactory.

Helo, I have the riva TNT2 M64 and the results for my computer, has a satisfactory.