Comment by welterde

That's perfectly possible with X11 to attach via VNC to an existing session. But what X11 over (local) network does way better than either RDP or VNC is to run individual applications remotely while having them seamlessly integrate with the rest of desktop. At the observatory for example we were running thin clients in the control room while all the control panel windows were coming from many different machines across the mountain and it felt like all the applications were running locally on the machine in the control room (while in reality nothing was running there).