mound builder vs gallinacean

mound builder and gallinacean both are nouns.

Word	Noun	Adjective	Verb	Adverb
mound builder	Yes	No	No	No
gallinacean	Yes	No	No	No

As nouns, gallinacean is a hypernym of mound builder; that is, gallinacean is a word with a broader meaning than mound builder:

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

Other hypernyms of mound builder include gallinaceous bird.

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