export duty vs duty

export duty and duty both are nouns.

Word	Noun	Adjective	Verb	Adverb
export duty	Yes	No	No	No
duty	Yes	No	No	No

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

Other hypernyms of export duty include tariff.

export duty (noun)	duty (noun)
a duty imposed on exports	the social force that binds you to the courses of action demanded by that force
	work that you are obliged to perform for moral or legal reasons
	a government tax on imports or exports