there both the same thing mate. nvidia bought ageia and then introduced it on there cards as physx. it still uses the same x86 code set that ageia used and this is what limits it to debris and cloth. nvidia really needs to move on to keep up with the better cpu based engines like havoc and frosbite.
what part of there the same dont you get... they are identical. if it works on nvida physx it works on agiea physics cards... the only difference is nvida is updating the hardware. much like adding a turbo to a ford focus. its still a ford focus just faster.