ape-man vs missing link

ape-man and missing link both are nouns.

Word	Noun	Adjective	Verb	Adverb
ape-man	Yes	No	No	No
missing link	Yes	No	No	No

As nouns, ape-man and missing link are synonyms defined as:

ape-man and missing link: hypothetical organism formerly thought to be intermediate between apes and human beings

ape-man (noun)	missing link (noun)
hypothetical organism formerly thought to be intermediate between apes and human beings	hypothetical organism formerly thought to be intermediate between apes and human beings
a person assumed to have been raised by apes