tawny owl vs bird of Minerva

tawny owl and bird of Minerva both are nouns.

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

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

tawny owl: reddish-brown European owl having a round head with black eyes
bird of Minerva: nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes

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

tawny owl (noun)	bird of Minerva (noun)
reddish-brown European owl having a round head with black eyes	nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes