let's ignore XP as a more glossy consumer version of 2000
That feels like a dangerous argument;
- 2000 = NT 5.0
- XP = NT 5.1
- XP x64 = NT 5.2
- Vista = NT 6.0
- 7 = NT 6.1
- 8 = NT 6.2
- 8.1 = NT 6.3
- 10 = NT 6.4 (Later NT 10.0 then 1507 for July 2015 when they made the switch to ‘agile’.)
Unless you are prepared to argue that everything since has just been an updated version of Vista.