illation vs deduction

illation and deduction both are nouns.

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

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

illation: the reasoning involved in drawing a conclusion or making a logical judgment on the basis of circumstantial evidence and prior conclusions rather than on the basis of direct observation
deduction: something that is inferred (deduced or entailed or implied)

Other hyponyms of illation include analogy, corollary, derivation, entailment, implication, extrapolation, presumption.

illation (noun)	deduction (noun)
the reasoning involved in drawing a conclusion or making a logical judgment on the basis of circumstantial evidence and prior conclusions rather than on the basis of direct observation	the act of subtracting (removing a part from the whole)
	the act of reducing the selling price of merchandise
	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