cutback vs diminution

cutback and diminution both are nouns.

Word	Noun	Adjective	Verb	Adverb
cutback	Yes	No	No	No
diminution	Yes	No	No	No

As nouns, diminution is a hypernym of cutback; that is, diminution is a word with a broader meaning than cutback:

Other hypernyms of cutback include decrease, reduction, step-down.

cutback (noun)	diminution (noun)
a reduction in quantity or rate	the act of decreasing or reducing something
	the statement of a theme in notes of lesser duration (usually half the length of the original)
	change toward something smaller or lower