The difference is that Physics on the gpu does not seperate gpu/cpu performance into seperate categories. A PPU cannot render graphics on it's own, so it is considered part of the cpu sub-system.

The whole point of that test is to measure CPU sub-system performance in rendering physics, and to isolate it from gpu performance. It says so right in the design documents, as I posted in the first thread we had here, when they started to pull the scores.