I never was into CP/M, but I knew it was very popular and the amount of software out there was significant. That being said, when you looked beyond the Kaypros, the IMSAIs, the SOLs and the like which were presumably built mostly similar (well, if you consider that they're all based on the 8080 or Z80), there were a few oddballs out there. In particular, you could add CP/M capabilities to 6502 based platforms such as the Apple II, C64, Amstrad, etc.
Was all software made for CP/M (8080) compatible across all these machines including the Apple/C64/etc variations? In other words, if you were to purchase WordStar on disk, could you boot it on a Kaypro just as easily as a C64 with the CP/M cartridge? I would presume all of the translation to KERNAL would be handled by the cartridge's BIOS.
Did this work seamlessly or was it a bit more complicated than that?