gallinule vs aquatic bird

gallinule and aquatic bird both are nouns.

Word	Noun	Adjective	Verb	Adverb
gallinule	Yes	No	No	No
aquatic bird	Yes	No	No	No

As nouns, aquatic bird is a hypernym of gallinule; that is, aquatic bird is a word with a broader meaning than gallinule:

gallinule: any of various small aquatic birds of the genus Gallinula distinguished from rails by a frontal shield and a resemblance to domestic hens
aquatic bird: wading and swimming and diving birds of either fresh or salt water

gallinule (noun)	aquatic bird (noun)
any of various small aquatic birds of the genus Gallinula distinguished from rails by a frontal shield and a resemblance to domestic hens	wading and swimming and diving birds of either fresh or salt water