shrinking vs reduction

shrinking and reduction both are nouns.

Word	Noun	Adjective	Verb	Adverb
shrinking	Yes	No	No	No
reduction	Yes	No	No	No

As nouns, reduction is a hypernym of shrinking; that is, reduction is a word with a broader meaning than shrinking:

Other hypernyms of shrinking include decrease, diminution, step-down.

shrinking (noun)	reduction (noun)
the act of becoming less	the act of decreasing or reducing something
process or result of becoming less or smaller	the act of reducing complexity
	any process in which electrons are added to an atom or ion (as by removing oxygen or adding hydrogen); always occurs accompanied by oxidation of the reducing agent