domestic fowl vs gallinacean

domestic fowl and gallinacean both are nouns.

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

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

domestic fowl: a domesticated gallinaceous bird thought to be descended from the red jungle fowl
gallinacean: heavy-bodied largely ground-feeding domestic or game birds

Other hypernyms of domestic fowl include gallinaceous bird.

domestic fowl (noun)	gallinacean (noun)
a domesticated gallinaceous bird thought to be descended from the red jungle fowl	heavy-bodied largely ground-feeding domestic or game birds