Strix nebulosa vs bird of night

Strix nebulosa and bird of night both are nouns.

Word	Noun	Adjective	Verb	Adverb
Strix nebulosa	Yes	No	No	No
bird of night	Yes	No	No	No

As nouns, bird of night is a hypernym of Strix nebulosa; that is, bird of night is a word with a broader meaning than Strix nebulosa:

Strix nebulosa: large dish-faced owl of northern North America and western Eurasia
bird of night: nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes

Other hypernyms of Strix nebulosa include bird of Minerva, hooter, owl.

Strix nebulosa (noun)	bird of night (noun)
large dish-faced owl of northern North America and western Eurasia	nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes