DFS vs DFS-R

I have read that it is possible to have DFS-R - replicating of folders -  without actually setting up a DFS name space.

Is that correct?

If correct, what would be gained or lost by doing the two in conjunction/separately?

I guess I'm asking is there any synergy between the two - is DFS-R better in some way if DFS is in place?  Is there a downside to DFS-R if DFS is in place? I understand the benefits of each on their own - just not sure what they bring to the table for each other.