tonnage duty vs tariff

tonnage duty and tariff both are nouns.

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

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

tonnage duty: a tax imposed on ships that enter the US; based on the tonnage of the ship
tariff: a government tax on imports or exports

Other hypernyms of tonnage duty include duty.

tonnage duty (noun)	tariff (noun)
a tax imposed on ships that enter the US; based on the tonnage of the ship	a government tax on imports or exports

tonnage duty (verb)	tariff (verb)
	charge a tariff