Historically, Microsoft has taken a similar support approach related to service packs. When a Windows service pack is released, Microsoft provides customers 24 months of support for the prior service pack or original release. Unlike service packs that are typically a collection of fixes, Windows 8.1 has new features and enhancements, and was designed to give customers the ability to deploy this update similar to service packs. Therefore we are applying the service pack policy to Windows 8.1.
Windows 8.1 does not change any hardware requirements compared with Windows 8 and existing Windows Store apps will work with Windows 8.1. Business customers who had Software Assurance licensing received Windows 8.1 as a free update.