painting vs impasto

painting and impasto both are nouns.

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

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

painting: creating a picture with paints
impasto: painting that applies the pigment thickly so that brush or palette knife marks are visible

painting (noun)	impasto (noun)
creating a picture with paints	painting that applies the pigment thickly so that brush or palette knife marks are visible
the occupation of a house painter
the act of applying paint to a surface
graphic art consisting of an artistic composition made by applying paints to a surface