Indeed semantics for pedantics but still there is some difference.
What I mean is:
You upgrade when you put something better in, more memory, bigger hard drive, extra or faster processor, etc.
Theoretically you could upgrade the Iyonix CPU (With CPUs on a PCI card but there's no support), also theoretically you could upgrade a A9Home (Replace the CPU/Memory piggyback with a faster one but that's not yet available) so there is no real difference there.
However you can not replace the CPU of an Iyonix as that is soldered to the board.