import duty vs tariff

import duty and tariff both are nouns.

Word	Noun	Adjective	Verb	Adverb
import duty	Yes	No	No	No
tariff	Yes	No	Yes	No

As nouns, tariff is a hypernym of import duty; that is, tariff is a word with a broader meaning than import duty:

Other hypernyms of import duty include duty.

import duty (noun)	tariff (noun)
a duty imposed on imports	a government tax on imports or exports

import duty (verb)	tariff (verb)
	charge a tariff