urethane vs ester

urethane and ester both are nouns.

Word	Noun	Adjective	Verb	Adverb
urethane	Yes	No	No	No
ester	Yes	No	No	No

As nouns, ester is a hypernym of urethane; that is, ester is a word with a broader meaning than urethane:

urethane: an ester of carbamic acid
ester: organic compound formed by reaction between an acid and an alcohol with elimination of water

urethane (noun)	ester (noun)
an ester of carbamic acid	organic compound formed by reaction between an acid and an alcohol with elimination of water