verification vs substantiation

verification and substantiation both are nouns.

Word	Noun	Adjective	Verb	Adverb
verification	Yes	No	No	No
substantiation	Yes	No	No	No

As nouns, verification and substantiation are synonyms defined as:

verification and substantiation: additional proof that something that was believed (some fact or hypothesis or theory) is correct

Other synonyms of verification include check, confirmation.

verification (noun)	substantiation (noun)
additional proof that something that was believed (some fact or hypothesis or theory) is correct	the act of validating; finding or testing the truth of something
(law) an affidavit attached to a statement confirming the truth of that statement	additional proof that something that was believed (some fact or hypothesis or theory) is correct