centaur vs mythical creature

centaur and mythical creature both are nouns.

Word	Noun	Adjective	Verb	Adverb
centaur	Yes	No	No	No
mythical creature	Yes	No	No	No

As nouns, mythical creature is a hypernym of centaur; that is, mythical creature is a word with a broader meaning than centaur:

centaur: (classical mythology) a mythical being that is half man and half horse
mythical creature: a monster renowned in folklore and myth

Other hypernyms of centaur include mythical monster.

centaur (noun)	mythical creature (noun)
(classical mythology) a mythical being that is half man and half horse	a monster renowned in folklore and myth