sandbox vs plaything

sandbox and plaything both are nouns.

Word	Noun	Adjective	Verb	Adverb
sandbox	Yes	No	No	No
plaything	Yes	No	No	No

As nouns, plaything is a hypernym of sandbox; that is, plaything is a word with a broader meaning than sandbox:

sandbox: a plaything consisting of a pile of sand or a box filled with sand for children to play in
plaything: an artifact designed to be played with

Other hypernyms of sandbox include toy.

sandbox (noun)	plaything (noun)
a plaything consisting of a pile of sand or a box filled with sand for children to play in	an artifact designed to be played with
mold consisting of a box with sand shaped to mold metal