I had to research..newbie as well ;) They're just different platforms. Links are as follows:
https://utopian.io/
https://busy.org/
https://d.tube/
you can log into each with your steemit id and password.
You will be prompted to use steemconnect and will be asked for steemit password. DON"T use the master password, use the activation key. You should not use the master unless really needed. Hope that helps.