Windows 8.1 'Blue': Is it a service pack, a redesign, or a rebranding? - I think that things are not as clear cut as that, and I believe that Windows "Blue" represents an effort on Microsoft's part to change the way we think of Windows and its update cycle.
One idea that we can dispel for sure is any notion that Windows "Blue" is a "new" version of Windows. It is not, and if nothing else, the version number being kicked up to 8.1 should remind us of that. Even Microsoft is referring to this release as "Windows 8.1". There's no way Microsoft could push a new version out of the door yearly.

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