RealityKit: Spaces vs Modes?

In RealityKit app mode, what are the differences between Shared / Immersive Spaces vs Shared / Exclusive Modes?

This page describes the difference between the modes. In shared mode, you can have multiple bounded volumes (which you might call “spaces,” though I don’t know if our docs use that terminology). In exclusive mode, you have one unbounded (or “immersive”) space (but can also have bounded volumes).

Yeah, I’ve read that doc. That’s actually what prompted my post. Sorry, I still don’t quite grasp the difference.

I think some diagrams like these would help:
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