driftage vs departure

driftage and departure both are nouns.

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

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

driftage: the deviation (by a vessel or aircraft) from its intended course due to drifting
departure: a variation that deviates from the standard or norm

Other hypernyms of driftage include deviation, difference, divergence.

driftage (noun)	departure (noun)
the deviation (by a vessel or aircraft) from its intended course due to drifting	the act of departing
	euphemistic expressions for death
	a variation that deviates from the standard or norm