pushover vs child's play

pushover and child's play both are nouns.

Word	Noun	Adjective	Verb	Adverb
pushover	Yes	No	No	No
child's play	Yes	No	No	No

As nouns, pushover and child's play are synonyms defined as:

Other synonyms of pushover include breeze, cinch, duck soup, picnic, piece of cake, snap, walkover.

pushover (noun)	child's play (noun)
any undertaking that is easy to do	any undertaking that is easy to do
someone who is easily taken advantage of	activity by children that is guided more by imagination than by fixed rules