alkene vs ethylene

alkene and ethylene both are nouns.

Word	Noun	Adjective	Verb	Adverb
alkene	Yes	No	No	No
ethylene	Yes	No	No	No

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

alkene: any unsaturated aliphatic hydrocarbon
ethylene: a flammable colorless gaseous alkene; obtained from petroleum and natural gas and used in manufacturing many other chemicals; sometimes used as an anesthetic

Other hyponyms of alkene include ethene, cycloalkene, cycloolefin, hexine.

alkene (noun)	ethylene (noun)
any unsaturated aliphatic hydrocarbon	a flammable colorless gaseous alkene; obtained from petroleum and natural gas and used in manufacturing many other chemicals; sometimes used as an anesthetic