Lego set vs plaything

Lego set and plaything both are nouns.

Word	Noun	Adjective	Verb	Adverb
Lego set	Yes	No	No	No
plaything	Yes	No	No	No

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

Lego set: (trademark) a child's plastic construction set for making mechanical models
plaything: an artifact designed to be played with

Other hypernyms of Lego set include toy.

Lego set (noun)	plaything (noun)
(trademark) a child's plastic construction set for making mechanical models	an artifact designed to be played with