polystyrene vs phenylethylene

polystyrene and phenylethylene both are nouns.

Word	Noun	Adjective	Verb	Adverb
polystyrene	Yes	No	No	No
phenylethylene	Yes	No	No	No

As nouns, phenylethylene is a hypernym of polystyrene; that is, phenylethylene is a word with a broader meaning than polystyrene:

Other hypernyms of polystyrene include cinnamene, styrene, vinylbenzene.

polystyrene (noun)	phenylethylene (noun)
a polymer of styrene; a rigid transparent thermoplastic	a colorless oily liquid; the monomer for polystyrene