Windows 8.1 is the "real" Windows OS that runs on PCs and tablets; it includes BACKWARD compatibility with most earlier Windows software -- programs and games that were designed to run on Windows 7, Vista, and XP. By contrast, Windows RT is a stripped-down version of Windows 8.1 that does not deliver that backward compatibility. (The reason: RT machines run ARM chips RATHER than full Intel or AMD "x86" CPUs, allowing them LONGER battery life and cheaper prices.) Instead, Windows RT only runs the apps available in the Windows Store (which, confusingly, is available in both 8.1 and RT). Notably, however, Windows RT includes a free copy of Microsoft Office 2013, which has been designed to run on both versions of Windows.

While there were a handful of devices that ran RT in 2012, so far, the Microsoft Surface and Surface 2 tablets appear to be the only RT machines currently available. (Again, ADDING to the confusion: the Surface Pro and Microsoft Surface Pro 2 tablets run full Windows 8.1.)

Windows 8.1 is the "real" Windows OS that runs on PCs and tablets; it includes backward compatibility with most earlier Windows software -- programs and games that were designed to run on Windows 7, Vista, and XP. By contrast, Windows RT is a stripped-down version of Windows 8.1 that does not deliver that backward compatibility. (The reason: RT machines run ARM chips rather than full Intel or AMD "x86" CPUs, allowing them longer battery life and cheaper prices.) Instead, Windows RT only runs the apps available in the Windows Store (which, confusingly, is available in both 8.1 and RT). Notably, however, Windows RT includes a free copy of Microsoft Office 2013, which has been designed to run on both versions of Windows.

While there were a handful of devices that ran RT in 2012, so far, the Microsoft Surface and Surface 2 tablets appear to be the only RT machines currently available. (Again, adding to the confusion: the Surface Pro and Microsoft Surface Pro 2 tablets run full Windows 8.1.)