drop-off vs shrinkage

drop-off and shrinkage both are nouns.

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

As nouns, shrinkage is a hyponym of drop-off; that is, shrinkage is a word with a more specific, narrower meaning than drop-off:

Other hyponyms of drop-off include shrinking, casualty, sinking, attrition, rarefaction, dwindling, dwindling away, waning.

drop-off (noun)	shrinkage (noun)
a change downward	the act of stealing goods that are on display in a store
a steep high face of rock	the amount by which something shrinks
a noticeable deterioration in performance or quality	process or result of becoming less or smaller