ballet master vs dancer

ballet master and dancer both are nouns.

Word	Noun	Adjective	Verb	Adverb
ballet master	Yes	No	No	No
dancer	Yes	No	No	No

As nouns, dancer is a hypernym of ballet master; that is, dancer is a word with a broader meaning than ballet master:

ballet master: a man who directs and teaches and rehearses dancers for a ballet company
dancer: a performer who dances professionally

Other hypernyms of ballet master include professional dancer, terpsichorean.

ballet master (noun)	dancer (noun)
a man who directs and teaches and rehearses dancers for a ballet company	a performer who dances professionally
	a person who participates in a social gathering arranged for dancing (as a ball)