Hi, You could try using [https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles?redirectlocale=en-US&redirectslug=Managing-profiles two (or more) profiles]. You can also [https://support.mozilla.org/en-US/kb/what-firefox-sync-and-how-do-i-use-it Sync] personal data, settings etc. between the profiles, or you could [https://support.mozilla.org/en-US/kb/Recovering%20important%20data%20from%20an%20old%20profile?s=profile&r=1&e=sph&as=s do it manually]. You can choose either Private browsing or the normal browsing, anyways the personal data, cookies, cache etc. are isolated from each other unless you choose to sync or copy manually. [https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data?e=sph&redirectlocale=en-US&as=s&s=profile&r=2&redirectslug=Profiles Profiles]

well, i did try it, created two profiles, the only problem seem you can not run both profiles on the same computer, unlike you can do with chrome. Maybe i should redifine my question, Is it possible to start, two completely different sessions of firefox.?? so one sesion has no idea what the other sesion is doing,

Use the -no-remote command line switch to open another Firefox instance with its own profile and to run different Firefox instances simultaneously. * http://kb.mozillazine.org/Opening_a_new_instance_of_Firefox_with_another_profile

Nice very nice