charge unit vs coulomb

charge unit and coulomb both are nouns.

Word	Noun	Adjective	Verb	Adverb
charge unit	Yes	No	No	No
coulomb	Yes	No	No	No

As nouns, coulomb is a hyponym of charge unit; that is, coulomb is a word with a more specific, narrower meaning than charge unit:

charge unit: a measure of the quantity of electricity (determined by the amount of an electric current and the time for which it flows)
coulomb: a unit of electrical charge equal to the amount of charge transferred by a current of 1 ampere in 1 second

Other hyponyms of charge unit include ampere-second, C, abcoulomb, ampere-minute, ampere-hour.

charge unit (noun)	coulomb (noun)
a measure of the quantity of electricity (determined by the amount of an electric current and the time for which it flows)	a unit of electrical charge equal to the amount of charge transferred by a current of 1 ampere in 1 second