departure vs expiry

departure and expiry both are nouns.

Word	Noun	Adjective	Verb	Adverb
departure	Yes	No	No	No
expiry	Yes	No	No	No

As nouns, expiry is a hypernym of departure; that is, expiry is a word with a broader meaning than departure:

Other hypernyms of departure include death, decease.

departure (noun)	expiry (noun)
the act of departing	the event of dying or departure from life
euphemistic expressions for death	a coming to an end of a contract period
a variation that deviates from the standard or norm