decrease vs shrinkage

decrease and shrinkage both are nouns.

Word	Noun	Adjective	Verb	Adverb
decrease	Yes	No	Yes	No
shrinkage	Yes	No	No	No

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

Other hyponyms of decrease include dip, drop, fall, free fall.

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

Other hyponyms of decrease include shrinking, casualty, sinking, attrition, rarefaction, dwindling, dwindling away, waning.

decrease (noun)	shrinkage (noun)
the act of decreasing or reducing something	the act of stealing goods that are on display in a store
the amount by which something decreases	the amount by which something shrinks
a change downward	process or result of becoming less or smaller
a process of becoming smaller or shorter

decrease (verb)	shrinkage (verb)
decrease in size, extent, or range
make become smaller