Save options confusion

I’m a bit baffled by Ardour3 numerous options to save sessions:

Save - save the current state of the session. Seems clear.

Save As - save a “snapshot” of the session, some intermediate state of the session.

Rename - Rename the session, obviously. I suppose all files are still kept in the original session directory so seems a bit messy. How is this different than Save As?

Snapshot… - Another way to save a snapshot (?) How is this different than
Save As and Rename?

Save template - Seems clear - save a template of number of tracks, plugins, etc to for future sessions.

However get this error when I try to do it:

ERROR]: Unable to Copy file
/mhome/sound/recording/ardour3/Mixer48/plugins/1259 to
(Can’t recursively copy directory)


Thanks for the references. Very useful.