My memory is that the parts were interchangable in hardware (presuming the speed was OK) but the performance was better at a given speed for the 68882 over the 68881. I never did any rendering on my Amigas, so my use of the floating point was rather limited. I skipped over the '020 when I was heavily into Amigas, leaping from a massively expanded A1000 (Rejuvinator, Spirit InBoard, Microbotics Starboard w/Star- Drive, ROM switcher, etc.) to an A3000/25.