David, They are one in the same. Also, expect an all together new chip every six months after it is out. The GeForce 256 is quoted as being four - ten times faster than a pentium III 550 on simple to complex lighting scenarios. Wait till 2 weeks after christmas and buy whatever you need. Now is not the time to buy a new card.
ARTICLE on GeForce 256:
http://www.zdnet.com/pcmag/stories/trends/0,7607,2326894,00.html
Steve stated, "Each forthcoming "standard" claims to be the best, and well, that really is a tall boast to make since it has yet to be seen --->
Well I updated from a TNT Viper 550 to aTNT2 Viper 770 Ultra, and although it is better and smoother and faster, it clearly was not a wise use of a couple hundred bucks. I could have bougtht three more copies of CM and gotten the other Panther print, the King Tiger and the Tiger Print. Also, not much difference between an Ultra TNT2 and a 3DFX card from my experience. Either TNT2 or 3DFX will excel for games optimized for them. Steve makes a great point. Even nVidia is coming out with a new program to release newer faster chips every six months.
The technology is exciting and will surely prove to take 3D video gaming to a new level, but Bitboys has a product in BETA for developers that threatens to displace both 3DFX and nVidia. It is 512 bit and nVidia is 256 bit. AND it was announced August 2, 1999. Here is an article:
http://www.bitboys.com/a_pr_glaze3d.html