this shit is confusing, what is the exact difference between RT and pro.
As others may have already said:
- WinRT has a limited desktop: Some desktop features are not available in the RT version (joining a domain, or being a host for remote desktop access for instance), the wRT desktop also won't allow you to run any of the currently desktop applications, except for the few ones that come pre-loaded with it (IE, Office, Explorer, paint...)
- Other than the preloaded applications, wRT can only install and run metro/modern ui apps. Those apps are usually distributed (but not limited to) the integrated app store. Those are mobile oriented apps, they are full screen, are developed with touch in mind, and follow a stricter set of rules on performance/battery life/security than a regular desktop application. They are more like the kind of applications that you would find on Android and iPads, than on windows 7.
- By default, the only way to install applications on wRT is through the app store. However, if you have a developer license, or purchase an additional license upgrade you can install metro applications bypassing the store. That way you can use your device for testing an application you are developing, or you can install a custom made application that was developed for you or your company.
The pro version has the same new platform where metro applications run (and likely with the same restrictions) but it has the same full featured desktop of the windows 7 (actually, it has a few more features, but you get the point

)
Hope i could help