Questions about workspaces and groups, what's the difference?

Questions about workspaces and groups, what's the difference?

Hello,
I'm confused about the whole Workspaces and Groups thing and I need some clarification please.  How are the two related and what is the difference between them?  When would I use one or the other, can you give me some examples?

Also, when it says "you can edit in real time", what exactly does that mean?  To me, real time means I can invite 4 users to a file (using a Group or Workspace, I don't know), start up a chat window, and then sit and discuss the file while we can all look at it and make edits at the same time, and see those edits as they are made.  Is that what this is talking about?  
Thanks