subtraction vs reduction

subtraction and reduction both are nouns.

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

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

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

subtraction (noun)	reduction (noun)
the act of subtracting (removing a part from the whole)	the act of decreasing or reducing something
an arithmetic operation in which the difference between two numbers is calculated	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