man-child vs kid

man-child and kid both are nouns.

Word	Noun	Adjective	Verb	Adverb
man-child	Yes	No	No	No
kid	Yes	No	Yes	No

As nouns, kid is a hypernym of man-child; that is, kid is a word with a broader meaning than man-child:

Other hypernyms of man-child include male, male person, child.

man-child (noun)	kid (noun)
a child who is male	young goat
	a young person of either sex
	a human offspring (son or daughter) of any age
	soft smooth leather from the hide of a young goat

man-child (verb)	kid (verb)
	be silly or tease one another
	tell false information to for fun