wash drawing vs water-colour

wash drawing and water-colour both are nouns.

Word	Noun	Adjective	Verb	Adverb
wash drawing	Yes	No	No	No
water-colour	Yes	No	No	No

As nouns, water-colour is a hypernym of wash drawing; that is, water-colour is a word with a broader meaning than wash drawing:

wash drawing: a watercolor made by applying a series of monochrome washes one over the other
water-colour: a painting produced with watercolors

Other hypernyms of wash drawing include water-color, watercolor, watercolour.

wash drawing (noun)	water-colour (noun)
a watercolor made by applying a series of monochrome washes one over the other	the art or technique of painting with watercolors
	a painting produced with watercolors
	a water-base paint (with water-soluble pigments); used by artists
	water-soluble pigment