functionality vs functional

functionality is a noun but functional is not a noun.

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

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

functionality (adjective)	functional (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