I was reading the specs about MS Surface and saw that there are two Models offered. One with Windows RT and one with Windows 8 Pro. I'm wondering what's the difference between those two OS?
From the Windows Blog post "Announcing Windows 8 Editions":
Wikipedia also has nice pretty tables with more details on the available features.
Full list of features in each version from the Microsoft blog post:
* Office Home & Student RT does not include support for Macros, Add-Ins, Forms and other features as listed in the FAQ.
† Only bundled Microsoft applications such as Notepad, Paint etc. can be executed in Desktop mode on Windows RT.
‡ Windows RT has no UI and very limited support for managing Bitlocker To Go drives (cut down version of manage-bde command is available).
If you're not sure whether a given program will work on your version of Windows, you can find more information in How can I tell which versions of Windows 8 a program will work on?
There seems to be some confusion on this topic, so I have attempted to clarify.
Windows RT is a variation of the Windows 8 operating system specifically designed for ARM(see bottom) devices. Since it is a distinct operating system, you will see Windows RT in place of Windows 8 when you look at the Settings -> PC Info screen of an ARM based tablet device (or similar). Earlier incarnations of the operating system were branded Windows on ARM.
Difference between "Windows RT" and "Windows 8":
From the end-user perspective there is not much difference as both support the Modern UI. Windows RT is not sold directly to consumers, but is meant to be sold to device manufacturers (aka OEMs) for preinstallation on devices. The goal behind Windows RT is to enable a consistent user experience across the range of tablets offered by manufacturers (including Microsoft's homegrown Surface). Windows RT will come bundled with Office, while Windows 8 users will have to buy (and install) it separately. The selection of bundled software differs between Windows RT and Windows 8. Windows RT seems to have stricter and different limitations on the software you are permitted to run on it, and it does not enable the use of the Win32 and COM APIs(see bottom). The WinRT API is available in stead.
I am working on a project requiring access to the underlying system information of an ARM device running Windows RT, and it appears to be possible to access a subset of the Win32 API. If it works, I will post my experience in a subsequent post.
A microprocessor architecture (actually a family of architectures). Other architectures are x86, x86_64/amd64, PowerPC and MIPS. There are several companies licensing the architecture and producing ARM chips, mostly for low-cost and/or low-power applications.
Application programming interface. If a specific API is unavailable, you will not be able to run software created for use with that API.
Windows RT is compiled to use an ARM CPU and only runs Metro apps. Windows 8 Pro is the standard Windows OS that runs on x86 processors (Intel, AMD, etc). It runs Metro apps as well as existing Windows applications.
Windows RT has been designed to work with ARM processors, while Windows 8 Pro is designed to work with x86 processors.
This Endgadget article points out some of the differences:
So it looks like the RT version of the tablet is a bit more energy efficient.
Windows RT is a version designed for ARM Processors, machines like tablets. Windows 8 will be the normal x86-x64 type.