butylene vs isobutylene

butylene and isobutylene both are nouns.

Word	Noun	Adjective	Verb	Adverb
butylene	Yes	No	No	No
isobutylene	Yes	No	No	No

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

butylene: any of three isomeric hydrocarbons C4H8; all used in making synthetic rubbers
isobutylene: used also in making gasoline components

Other hyponyms of butylene include polybutene, polybutylene.

butylene (noun)	isobutylene (noun)
any of three isomeric hydrocarbons C4H8; all used in making synthetic rubbers	used also in making gasoline components