functional vs functionality

functional is not a noun while functionality is a noun.

Word	Noun	Adjective	Verb	Adverb
functional	No	Yes	No	No
functionality	Yes	No	No	No

functional (noun)	functionality (noun)
	capable of serving a purpose well

functional (adjective)	functionality (adjective)
designed for or capable of a particular function or use
involving or affecting function rather than physiology
relating to or based on function especially as opposed to structure
(of e.g. a machine) performing or capable of performing
designed for or adapted to a function or use
fit or ready for use or service