What, *specifically* does Windows 8's “Refresh Your PC” option delete and retain?

I'm asking this question because I could only find non-technical, and non-specific, answers no more detailed than the options given by the OS. If you have an issue with your Windows 8 Pro machine and you want to restore it to a relatively clean slate, Microsoft provides you with two options:

a) "Restore Your PC" - Saving you the trouble of popping in a DVD, this takes the system to a new state (nothing installed on it but the base OS).

b) "Refresh Your PC" - This will save 'personal settings' but, and here's why I've posted this question, Apps you installed from discs or websites will be removed.

Now, in regards to (b): does this mean it will wipe all directories it finds that it didn't install from the Windows App Store?

Or does it mean it will go through uninstallation procedures of the various apps?

Or does it mean something else?

Why is this important? Well, this is critical from the perspective of knowing whether application data (which is what we care about) will be removed.

Thanks