duty assignment vs duty

duty assignment and duty both are nouns.

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

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

duty assignment: a duty that you are assigned to perform (especially in the armed forces)
duty: work that you are obliged to perform for moral or legal reasons

duty assignment (noun)	duty (noun)
a duty that you are assigned to perform (especially in the armed forces)	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