horned owl vs bird of night

horned owl and bird of night both are nouns.

Word	Noun	Adjective	Verb	Adverb
horned owl	Yes	No	No	No
bird of night	Yes	No	No	No

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

horned owl: large owls having prominent ear tufts
bird of night: nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes

Other hypernyms of horned owl include bird of Minerva, hooter, owl.

horned owl (noun)	bird of night (noun)
large owls having prominent ear tufts	nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes