These two values are completely indistinguishable. That's good for a
timestamp (they are the same time after all). But they are not a
"timestamp with time zone". The time zone is not part of the value but
of the environment.
No, it’s inherent to the data type itself. The data type has an implied time zone of UTC. That is a reasonable definition of “with” in my book. If I see “20:05” I need to know the type of data to know whether its a time or interval - values without types are incomplete. i.e., the type can supply relevant context, like a reference time zone.
David J.