Help understanding "automated backup storage" vs. "Save to"

Using Moodle 2.4.5.

I have automated backups turned on and they seem to work since I get the regular email.  However, I don't understand enough about how they are configured.  The Docs have a big hole regarding the location of the backup information.

In the configs, what is the difference between the "Automated backup storage" and the "Save to" box?  Both of those things seem to be asking the same thing: where do you want the backups stored, but they also seem to be talking about specifying different locations.  Hence, my confusion...

Second (if you don't mind): where can I get information about the three choices in the "Automated backup storage" dropdown?  Again, the Docs are less than helpful in this case.

Thanks as ever!