mythical being vs houri

mythical being and houri both are nouns.

Word	Noun	Adjective	Verb	Adverb
mythical being	Yes	No	No	No
houri	Yes	No	No	No

As nouns, houri is a hyponym of mythical being; that is, houri is a word with a more specific, narrower meaning than mythical being:

mythical being: an imaginary being of myth or fable
houri: (Islam) one of the dark-eyed virgins of perfect beauty believed to live with the blessed in Paradise

Other hyponyms of mythical being include halcyon, mythical creature, mythical monster, phoenix, Amazon, Gog and Magog, golem, hero.

mythical being (noun)	houri (noun)
an imaginary being of myth or fable	a voluptuously beautiful young woman
	(Islam) one of the dark-eyed virgins of perfect beauty believed to live with the blessed in Paradise