extra vs additive

extra and additive both are nouns.

Word	Noun	Adjective	Verb	Adverb
extra	Yes	Yes	No	Yes
additive	Yes	Yes	No	No

extra (noun)	additive (noun)
something additional of the same kind	something added to enhance food or gasoline or paint or medicine
an additional edition of a newspaper (usually to report a crisis)
a minor actor in crowd scenes

extra (adjective)	additive (adjective)
further or added	characterized or produced by addition
more than is needed, desired, or required	designating or involving an equation whose terms are of the first degree
added to a regular schedule

extra (adverb)	additive (adverb)
unusually or exceptionally