incidental vs inessential

incidental and inessential both are nouns.

Word	Noun	Adjective	Verb	Adverb
incidental	Yes	Yes	No	No
inessential	Yes	Yes	No	No

incidental (noun)	inessential (noun)
an item that is incidental	anything that is not essential
(frequently plural) an expense not budgeted or not specified

incidental (adjective)	inessential (adjective)
(sometimes followed by `to') minor or casual or subordinate in significance or nature or occurring as a chance concomitant or consequence	not basic or fundamental
not of prime or central importance	not absolutely necessary
occurring with or following as a consequence