art vs painting

art and painting both are nouns.

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

As nouns, painting is a hyponym of art; that is, painting is a word with a more specific, narrower meaning than art:

art (noun)	painting (noun)
the creation of beautiful or significant things	creating a picture with paints
the products of human creativity; works of art collectively	the occupation of a house painter
a superior skill that you can learn by study and practice and observation	the act of applying paint to a surface
photographs or other visual representations in a printed publication	graphic art consisting of an artistic composition made by applying paints to a surface