butene vs polybutylene

butene and polybutylene both are nouns.

Word	Noun	Adjective	Verb	Adverb
butene	Yes	No	No	No
polybutylene	Yes	No	No	No

As nouns, polybutylene is a hyponym of butene; that is, polybutylene is a word with a more specific, narrower meaning than butene:

butene: any of three isomeric hydrocarbons C4H8; all used in making synthetic rubbers
polybutylene: a polymer of butylene; used in lubricants and synthetic rubber

Other hyponyms of butene include isobutylene, polybutene.

butene (noun)	polybutylene (noun)
any of three isomeric hydrocarbons C4H8; all used in making synthetic rubbers	a polymer of butylene; used in lubricants and synthetic rubber