Asio otus vs bird of night

Asio otus and bird of night both are nouns.

Word	Noun	Adjective	Verb	Adverb
Asio otus	Yes	No	No	No
bird of night	Yes	No	No	No

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

Asio otus: slender European owl of coniferous forests with long 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 Asio otus include bird of Minerva, hooter, owl.

Asio otus (noun)	bird of night (noun)
slender European owl of coniferous forests with long ear tufts	nocturnal bird of prey with hawk-like beak and claws and large head with front-facing eyes