feral man vs ape-man

feral man and ape-man both are nouns.

Word	Noun	Adjective	Verb	Adverb
feral man	Yes	No	No	No
ape-man	Yes	No	No	No

As nouns, ape-man is a hyponym of feral man; that is, ape-man is a word with a more specific, narrower meaning than feral man:

Other hyponyms of feral man include wolf boy.

feral man (noun)	ape-man (noun)
a person who is not socialized	hypothetical organism formerly thought to be intermediate between apes and human beings
	a person assumed to have been raised by apes