They can run concurrently and are completely isolated. I don't think this is possible with firefox yet. I use app mode since I don't need the normal navigation when using it this way.
and pull up the profile manager (you have to make sure all instances of Firefox are closed first) and you can create as many profiles as you want. Once you have a profile (for example, "worktrello") you can launch it with
firefox -P "worktrello" -no-remote
and it will be a completely separate process, with its own cache and cookies and all.
For example, I have a work-trello and a personal-trello command in ~/bin, but you can use shortcuts in Windows or whatever the equivalent is in OS X.
chromium-browser --app=https://trello.com --user-data-dir=/home/jewel/.profiles/personal-trello
They can run concurrently and are completely isolated. I don't think this is possible with firefox yet. I use app mode since I don't need the normal navigation when using it this way.