Roon confusion

I'm a bit confused about what Roon and its endpoints are doing in certain configurations.  First I should probably summarize the development of  my systems over the past few years.

1. Originally I was running a networked media server with audio and video content.  The video fed several streamer boxes driving TVs.  The audio fed my DAC directly via coax from a sound card.  I used Foobar and eventually JRiver for the audio.

2. Got rid of streamer boxes on TVs and went to Plex for video.  Set up a BlueOS environment for audio.  This entailed 2 Node 2i's on different audio systems and a TV soundbar.  Started using Qobuz, Tidal etc.  CDs started getting dustier and networked audio library fell into disuse.

3. Replaced one of the Node 2i's with Lumin U1 mini on reference system.  Major improvement in SQ.

Now the Roon question arises.  Seems a lot of people are using it with Lumin products and the Bluesound stuff would also work as endpoints.  But somehow it's not clear to me exactly what's going on.  These endpoints are streamers in their own right.  Let's say I make the network server the Roon core and I'm listening to Qobuz.  Is the core working as a kind of master control for the endpoint streamer, telling it to stream Qobuz as directed by Roon?  Or is Roon sending the actual  Qobuz stream to the streamer which just passes it on to the DAC?  Or something else? 

Kinda confusing, hope this is clear.  Comments welcome, thanks in advance.  Cheers,