This version of Windows is for OEM Devices only.
It is a locked down version of Windows 8 but for ARM devices like the Microsoft Surface RT.
You can only install software from the Windows Store. The familiar Desktop and most basic applications are included such as the Explorer, Notepad, Paint.
It also includes a stripped down version of Microsoft Office 2013 called Office RT, only Word, Excel, PowerPoint and OneNote.
Microsoft includes their regular Modern Apps that come with the full Windows.
OEM's can also include additional Apps for the Modern Interface.
Due to a bug in the Surface RT 8.1 update which left the device in a unbootable state, you could only recover when you restored your machine, but you needed the original Recovery Image but during the Update the recovery image is overwritten so Microsoft released the Recovery Files for a short time, from that we now know that there are 7 regions with their included languages.
Here is a list of what is in each package:
Surface RT 8.0 Asia = Chinese (Hong Kong SAR), Korean, Ukrainian
Surface RT 8.0 SE Asia = Indonesian, Malay (Malaysia)
Surface RT 8.0 Nordic = Danish, Finnish, Norwegian (Bokmal), Norwegian (Nyorsk)
Surface RT 8.0 Euro = German, Dutch, English-UK, French, Irish
Surface RT 8.0 North America = English
Surface RT 8.0 Mediterranean = Portuguese (Portugal), Spanish
Surface RT 8.0 CEE1 = Slovak, Czech, Turkish
Microsoft Surface RT 8.0 Recovery Image
MD5 SE Asia
MD5 North America
There are more images available in the gallery.