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