scrub fowl vs gallinacean

scrub fowl and gallinacean both are nouns.

Word	Noun	Adjective	Verb	Adverb
scrub fowl	Yes	No	No	No
gallinacean	Yes	No	No	No

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

scrub fowl: 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 scrub fowl include gallinaceous bird.

scrub fowl (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