"Boss" means somebody in charge.
"Chairman" usually means the leader of a committee (e.g. a board of directors).
"Administrator" means someone who covers administrative work, e.g. paperwork, filing etc.
"Master" means someone who owns a pet (e.g. the dog ran to its master), a martial arts master, someone who is an expert at something (e.g. he is a master of baking).
"Chief" means more or less what boss means.
A "manager" manages something, e.g. the shop manager.
A "head" is a boss of a department (usually) e.g. the head of marketing.
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