jacks vs child's game

jacks and child's game both are nouns.

Word	Noun	Adjective	Verb	Adverb
jacks	Yes	No	No	No
child's game	Yes	No	No	No

As nouns, child's game is a hypernym of jacks; that is, child's game is a word with a broader meaning than jacks:

jacks: a game in which jackstones are thrown and picked up in various groups between bounces of a small rubber ball
child's game: a game enjoyed by children

jacks (noun)	child's game (noun)
a game in which jackstones are thrown and picked up in various groups between bounces of a small rubber ball	a game enjoyed by children