diplomatic mission vs delegacy

diplomatic mission and delegacy both are nouns.

Word	Noun	Adjective	Verb	Adverb
diplomatic mission	Yes	No	No	No
delegacy	Yes	No	No	No

As nouns, delegacy is a hypernym of diplomatic mission; that is, delegacy is a word with a broader meaning than diplomatic mission:

Other hypernyms of diplomatic mission include commission, delegation, deputation, mission.

diplomatic mission (noun)	delegacy (noun)
a mission serving diplomatic ends	the appointment of a delegate
	a group of representatives or delegates
	the state of serving as an official and authorized delegate or agent