You can have multiple Firefox profiles, each containing a separate set of user information. The Profile Manager allows you to create, remove, rename, and switch profiles. If you have (or plan to have) multiple installations of Firefox on one computer, see Dedicated profiles per Firefox installation.
Why do I have multiple Firefox profiles?
There is a datalimit on our user profiles. The problem is that Firefox uses all the space from the user profile. This causes a storage space error every two days. To solve it, I open Firefox profile manager, multiple profiles are visible.Sep 19, 2014
How do I switch profiles in Firefox?