True, especially if you're looking at what's "under the hood". But visually, there are a lot of continuities between the two, and of course the user base large

True, especially if you're looking at what's "under the hood". But visually, there are a lot of continuities between the two, and of course the user base largely transitioned as if 9->X were just another upgrade like going from 6.0.7 to System 7.