While there were some rumors [WinBeta] that Windows 8.1 Update 2 would be distributed through the Windows Store with a potential 3 GB file size, it appears this will not be case. While Windows 8.1 was distributed through the Windows Store, Windows 8.1 Update 1 was distributed through Windows Update.
Microsoft appears to prefer distribution through Windows Update since some business/enterprise customers have disabled the Windows Store for their users. Since Update 2 is being distributed through Windows Update it will be free, also as expected. It also appears that the final name will be “Update 2″ and not Windows 8.2.
It is rumored that Microsoft will offer a significant discount to those upgrading from Windows 8.1 Update 2 to Windows 9. Those upgrading from any version prior to Update 2 will pay more.
Update 2 is expected to contain optimizations to make Windows 8 work better on small tablets, such as the Surface mini. It is rumored that Microsoft may be working on an “Update 3″ which will backport some Windows 9 features.
Source: RU Board