idiot box vs television set

idiot box and television set both are nouns.

Word	Noun	Adjective	Verb	Adverb
idiot box	Yes	No	No	No
television set	Yes	No	No	No

As nouns, idiot box and television set are synonyms defined as:

idiot box and television set: an electronic device that receives television signals and displays them on a screen

Other synonyms of idiot box include boob tube, goggle box, television, television receiver, telly, tv, tv set.

idiot box (noun)	television set (noun)
an electronic device that receives television signals and displays them on a screen	an electronic device that receives television signals and displays them on a screen