tiddlywinks vs child's game

tiddlywinks and child's game both are nouns.

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

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

tiddlywinks: a game in which players try to flip plastic disks into a cup by pressing them on the side sharply with a larger disk
child's game: a game enjoyed by children

tiddlywinks (noun)	child's game (noun)
a game in which players try to flip plastic disks into a cup by pressing them on the side sharply with a larger disk	a game enjoyed by children