shrinking vs step-down

shrinking and step-down both are nouns.

Word	Noun	Adjective	Verb	Adverb
shrinking	Yes	No	No	No
step-down	Yes	No	No	No

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

Other hypernyms of shrinking include decrease, diminution, reduction.

shrinking (noun)	step-down (noun)
the act of becoming less	the act of decreasing or reducing something
process or result of becoming less or smaller