illustration vs art

illustration and art both are nouns.

Word	Noun	Adjective	Verb	Adverb
illustration	Yes	No	No	No
art	Yes	No	No	No

As nouns, art is a hypernym of illustration; that is, art is a word with a broader meaning than illustration:

Other hypernyms of illustration include artwork, graphics, nontextual matter.

illustration (noun)	art (noun)
a visual representation (a picture or diagram) that is used to make some subject more pleasing or easier to understand	the creation of beautiful or significant things
an item of information that is typical of a class or group	the products of human creativity; works of art collectively
artwork that helps make something clear or attractive	a superior skill that you can learn by study and practice and observation
showing by example	photographs or other visual representations in a printed publication