polychrome vs colorful

polychrome is a noun but colorful is not a noun.

Word	Noun	Adjective	Verb	Adverb
polychrome	Yes	Yes	Yes	No
colorful	No	Yes	No	No

polychrome (noun)	colorful (noun)
a piece of work composed of or decorated in many colors

polychrome (adjective)	colorful (adjective)
having or exhibiting many colors	having much or varied color
	having color or a certain color; sometimes used in combination
	striking in variety and interest

polychrome (verb)	colorful (verb)
color with many colors; make polychrome