due date vs maturity date

due date and maturity date both are nouns.

Word	Noun	Adjective	Verb	Adverb
due date	Yes	No	No	No
maturity date	Yes	No	No	No

As nouns, due date and maturity date are synonyms defined as:

due date and maturity date: the date on which an obligation must be repaid

Other synonyms of due date include maturity.

due date (noun)	maturity date (noun)
the date on which an obligation must be repaid	the date on which an obligation must be repaid