driftage vs divergence

driftage and divergence both are nouns.

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

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

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

Other hypernyms of driftage include departure, deviation, difference.

driftage (noun)	divergence (noun)
the deviation (by a vessel or aircraft) from its intended course due to drifting	the act of moving away in different direction from a common point
	a difference between conflicting facts or claims or opinions
	an infinite series that has no limit
	a variation that deviates from the standard or norm