What is the difference between 'session' and 'workspace'?

I expected ‘sessions’ to be a set of ‘workspaces’, but if I save a session, it doesn’t load the workspaces that were open. Can someone clarify what the difference is? I know that a workspace is a persp workspace, it’s what is covered by Doom’s session that I’m unclear on. When I load a session, I only get one of the workspaces that was loaded at save time.

A session should indeed be a set of workspaces, and that is how session persistence works in vanilla Doom. If that isn’t the case for you, it sounds like it might be worth filing an issue for it, but since I cannot reproduce any misbehavior in vanilla Doom, I suspect it may be a personal configuration issue. See if any of these help (and check the *Messages* buffer for errors/warnings) after restoring a session.