barn owl vs bird of Minerva

barn owl and bird of Minerva both are nouns.

Word	Noun	Adjective	Verb	Adverb
barn owl	Yes	No	No	No
bird of Minerva	Yes	No	No	No

As nouns, bird of Minerva is a hypernym of barn owl; that is, bird of Minerva is a word with a broader meaning than barn owl:

barn owl: mottled buff and white owl often inhabiting barns and other structures; important in rodent control
bird of Minerva: nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes

Other hypernyms of barn owl include bird of night, hooter, owl.

barn owl (noun)	bird of Minerva (noun)
mottled buff and white owl often inhabiting barns and other structures; important in rodent control	nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes