mallee fowl vs mound-bird

mallee fowl and mound-bird both are nouns.

Word	Noun	Adjective	Verb	Adverb
mallee fowl	Yes	No	No	No
mound-bird	Yes	No	No	No

As nouns, mound-bird is a hypernym of mallee fowl; that is, mound-bird is a word with a broader meaning than mallee fowl:

mallee fowl: Australian mound bird; incubates eggs naturally in sandy mounds
mound-bird: large-footed short-winged birds of Australasia; build mounds of decaying vegetation to incubate eggs

Other hypernyms of mallee fowl include megapode, mound bird, mound builder, scrub fowl.

mallee fowl (noun)	mound-bird (noun)
Australian mound bird; incubates eggs naturally in sandy mounds	large-footed short-winged birds of Australasia; build mounds of decaying vegetation to incubate eggs