From a software API and security point of view, how does a Win8 metro app differ from a Windows7 app?

Question

For various app-stores (eg Play, iOS Store) downloadable apps may only be run in a sandbox - restrictions limit access to OS features, APIs, and other ways not suffered by native applications.

How does the software environment of downloadable Win8 Metro apps differ from, say, a Windows 7 software installer? Can they install device drivers, access the whole file system, can I download apps from the MS store that run in the Win7-style portion of the OS, etc...

Basically, I'm looking for what a Win7 developer needs to know about Win8.

Answer 1

Windows 8 store apps doesn't have access to same API's as the regular Windows 7/8 (WPF/WinForms) application does. The access to devices and other OS features is restricted. You cannot connect to a local database or contact a local running service from your Windows 8 store application. So it's very limiting in comparison to Windows 7 development environment.