illation vs entailment

illation and entailment both are nouns.

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

As nouns, entailment is a hyponym of illation; that is, entailment 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
entailment: something that is inferred (deduced or entailed or implied)

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

illation (noun)	entailment (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	something that is inferred (deduced or entailed or implied)