The difference is that the GripNut doesn't let you have spacers or hangers. The 2Nut has a more traditional design which allows for these between the adjustable race and top nut.
To use the GripNut, you need do cut the steerer to the exact right length. Can’t use spacers, hangers, or headsets with a higher stack afterwards anymore. Tricky business.
Yeah this a 2nut not a gripnut:
The difference is that the GripNut doesn't let you have spacers or hangers. The 2Nut has a more traditional design which allows for these between the adjustable race and top nut.