willing vs voluntary

willing and voluntary both are nouns.

Word	Noun	Adjective	Verb	Adverb
willing	Yes	Yes	No	No
voluntary	Yes	Yes	No	No

willing (noun)	voluntary (noun)
the act of making a choice	composition (often improvised) for a solo instrument (especially solo organ) and not a regular part of a religious service or musical performance
	(military) a person who freely enlists for service

willing (adjective)	voluntary (adjective)
disposed or inclined toward	of your own free will or design; done by choice; not forced or compelled
not brought about by coercion or force	controlled by individual volition