due vs overdue

due is a noun but overdue is not a noun.

Word	Noun	Adjective	Verb	Adverb
due	Yes	Yes	No	Yes
overdue	No	Yes	No	No

due (noun)	overdue (noun)
that which is deserved or owed
a payment that is due (e.g., as the price of membership)

due (adjective)	overdue (adjective)
owed and payable immediately or on demand	past due; not paid at the scheduled time
suitable to or expected in the circumstances
capable of being assigned or credited to
scheduled to arrive

due (adverb)	overdue (adverb)
directly or exactly; straight