RND...both myself and MS don't really differentiate between the terms...they see the next OS as an 'update'...and this current PUSH to coerce people to 10 by making it free is to get past the situation they had with 8 ....that altogether too many people stayed with 7 or worse still....'down graded' from 8 back to 7.
The sooner MS gets its user base ALL on the same platform - the better - FOR THEM...
Supporting legacy OS [plural] is a pain....and not just for them but for third party devs too...