useable vs functional

useable and functional both are adjectives.

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

As adjectives, useable and functional are synonyms defined as:

Other synonyms of useable include operable, operational, usable.

useable (adjective)	functional (adjective)
convenient for use or disposal	designed for or capable of a particular function or use
fit or ready for use or service	involving or affecting function rather than physiology
capable of being put to use	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