One of the biggest differences between FB and Steemit is censorship.  Other than crowd censorship, by people flagging content, there is none here. 

On FB you cannot post some things (nudity comes to mind) and then what is posted is reviewed by them and if they don't like it, they will either delete it or bury it so no-one ever sees it.

Also, not everything you post on FB is seen by your followers. It never shows up in their timeline. To me, that is another form of censorship.

Putting aside the potential for making money, Steemit is much more open and free than FB.