There's probably an entire department within Microsoft that makes their own alphabets and number systems. 95 comes after 3.1, right, but before 10? And XP is bigger than 365 but smaller than One? If you have a series of something, it obviously stands to reason that X is bigger than Vista.
But fret not, there's an easy shortcut to see which Microsoft product is newer. Just try them side by side and whichever has more advertisements is newer.