attrition vs drop-off

attrition and drop-off both are nouns.

Word	Noun	Adjective	Verb	Adverb
attrition	Yes	No	No	No
drop-off	Yes	No	No	No

As nouns, drop-off is a hypernym of attrition; that is, drop-off is a word with a broader meaning than attrition:

Other hypernyms of attrition include decrease, lessening.

attrition (noun)	drop-off (noun)
the act of rubbing together; wearing something down by friction	a change downward
a wearing down to weaken or destroy	a steep high face of rock
sorrow for sin arising from fear of damnation	a noticeable deterioration in performance or quality
the wearing down of rock particles by friction due to water or wind or ice
erosion by friction