mallee hen vs mallee fowl

mallee hen and mallee fowl both are nouns.

Word	Noun	Adjective	Verb	Adverb
mallee hen	Yes	No	No	No
mallee fowl	Yes	No	No	No

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

mallee hen: adult female mallee fowl
mallee fowl: Australian mound bird; incubates eggs naturally in sandy mounds

Other hypernyms of mallee hen include leipoa, Leipoa ocellata, lowan.

mallee hen (noun)	mallee fowl (noun)
adult female mallee fowl	Australian mound bird; incubates eggs naturally in sandy mounds