Postgresql: Difference between pg_dump and backup/restore? Don't they essentially do the same thing by storing all the data in a file and dumping it into another database? Is it that pg_dump just adds the data on to whatever is already there and restore deletes everything and then dumps it in?
pg_dump is the basic official tool of the project to create backups of PostgreSQL databases (or selected objects in it) in the file system.

To restore, you can either use pg_restore or simply psql, depending on the format of the backup.

The "Backup" and "Restore" options of pgAdmin are just fronts to the above mentioned tools.

There is no (official) tool "backup" or "restore" like you seem to be implying. You are probably confusing terms.