Run TorBrowsers' Tor independently from an installed Tor
Run TorBrowser completely independent from local Tor versions.
If a local Tor version is running a user that launches TorBrowser is prompted for a password.
By default a local install is protected by a password that is set automatically; in other words it's unknown. Another reason could be that the local Tor is not configured for being used as client. (Relay only)
It's useful for systems that can't use a local Firefox installation with TorButton. This is more user-friendly, too.