gallinacean vs megapode

gallinacean and megapode both are nouns.

Word	Noun	Adjective	Verb	Adverb
gallinacean	Yes	No	No	No
megapode	Yes	No	No	No

As nouns, megapode is a hyponym of gallinacean; that is, megapode is a word with a more specific, narrower meaning than gallinacean:

gallinacean: heavy-bodied largely ground-feeding domestic or game birds
megapode: large-footed short-winged birds of Australasia; build mounds of decaying vegetation to incubate eggs

gallinacean (noun)	megapode (noun)
heavy-bodied largely ground-feeding domestic or game birds	large-footed short-winged birds of Australasia; build mounds of decaying vegetation to incubate eggs