Postmaster :: Postmaster (n.) One who has charge of a station for the accommodation of travelers; one who supplies post horses.
Postmaster :: Postmaster (n.) One who has charge of a post office, and the distribution and forwarding of mails..
Postmaster-general :: Postmaster-general (n.) The chief officer of the post-office department of a government. In the United States the postmaster-general is a member of the cabinet.