unicorn vs imaginary being

unicorn and imaginary being both are nouns.

Word	Noun	Adjective	Verb	Adverb
unicorn	Yes	No	No	No
imaginary being	Yes	No	No	No

As nouns, imaginary being is a hypernym of unicorn; that is, imaginary being is a word with a broader meaning than unicorn:

unicorn: an imaginary creature represented as a white horse with a long horn growing from its forehead
imaginary being: a creature of the imagination; a person that exists only in legends or myths or fiction

Other hypernyms of unicorn include imaginary creature.

unicorn (noun)	imaginary being (noun)
an imaginary creature represented as a white horse with a long horn growing from its forehead	a creature of the imagination; a person that exists only in legends or myths or fiction