principal vs master

principal and master both are nouns.

Word	Noun	Adjective	Verb	Adverb
principal	Yes	Yes	No	No
master	Yes	Yes	Yes	No

As adjectives, principal and master are synonyms defined as:

Other synonyms of principal include chief, main, primary.

As nouns, master is a hyponym of principal; that is, master is a word with a more specific, narrower meaning than principal:

Other hyponyms of principal include chancellor, headmaster, schoolmaster, headmistress.

principal (noun)	master (noun)
the educator who has executive authority for a school	an original creation (i.e., an audio recording) from which copies can be made
an actor who plays a principal role	key that secures entrance everywhere
the major party to a financial transaction at a stock exchange; buys and sells for his own account	an artist of consummate skill
(criminal law) any person involved in a criminal offense, regardless of whether the person profits from such involvement	a combatant who is able to defeat rivals
the original amount of a debt on which interest is calculated	an authority qualified to teach apprentices
capital as contrasted with the income derived from it	directs the work of others
	a person who has general authority over others
	someone who holds a master's degree from academic institution
	presiding officer of a school
	an officer who is licensed to command a merchant ship

principal (adjective)	master (adjective)
most important element	most important element

principal (verb)	master (verb)
	have a firm understanding or knowledge of; be on top of
	be or become completely proficient or skilled in
	get on top of; deal with successfully
	have dominance or the power to defeat over