@ipaschke @thomasfuchs Does Mac Classic count as an older version of the same OS as Mac OSX and beyond? That was a major rewrite that kept the same name for branding reasons. What about the Windows 9x series vs Windows NT series, are they the same?
I like that this answer implies that vintage computers should be somewhat dissimilar to a current computer, but I think there are still some common cases where this leaves things ambiguous.