The Microsoft Surface table has been out for more than a half year now and is offered in two models, the Pro and RT (short for RunTime). The Pro version is more of a mini laptop that can be used for high production input with the portability of a slim-line tablet. The RT, on the other hand, is more of a consumption device and offers apps from Windows Apps store – which apparently does not have the number of catalog items as the Apple App Store and Google Play Store (see May report from Canalys).
For a quick comparison between the models, Microsoft provides the following page:
For an overview to the two, this YouTube clip from Which? does a pretty good job.
For a comparison among other mobile devices, see the following page: