Windows RT is windows tablet edition. It's the same as Windows 8, except it can only run Windows Store apps and Microsoft Office. The reason for the limitation is that RT tablets run on a different CPU that is not compatible with x86. So only apps written to the common WinRT api will work on them.
You can't buy a laptop with Windows RT. Windows RT is not sold separately. You can only get it with a device, such as a tablet. And, they will not ship it on anything that does not have a touch interface.