supplement vs supplemental

supplement is a noun but supplemental is not a noun.

Word	Noun	Adjective	Verb	Adverb
supplement	Yes	No	Yes	No
supplemental	No	Yes	No	No

supplement (noun)	supplemental (noun)
a supplementary component that improves capability
a quantity added (e.g. to make up for a deficiency)
textual matter that is added onto a publication; usually at the end

supplement (adjective)	supplemental (adjective)
	added to complete or make up a deficiency
	functioning in a supporting capacity

supplement (verb)	supplemental (verb)
add to the very end
add as a supplement to what seems insufficient
serve as a supplement to