diminution vs deduction

diminution and deduction both are nouns.

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

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

diminution (noun)	deduction (noun)
the act of decreasing or reducing something	the act of subtracting (removing a part from the whole)
the statement of a theme in notes of lesser duration (usually half the length of the original)	the act of reducing the selling price of merchandise
change toward something smaller or lower	reasoning from the general to the particular (or from cause to effect)
	something that is inferred (deduced or entailed or implied)
	an amount or percentage deducted
	a reduction in the gross amount on which a tax is calculated; reduces taxes by the percentage fixed for the taxpayer's income bracket