skin colour vs coloring

skin colour and coloring both are nouns.

Word	Noun	Adjective	Verb	Adverb
skin colour	Yes	No	No	No
coloring	Yes	No	No	No

As nouns, coloring is a hypernym of skin colour; that is, coloring is a word with a broader meaning than skin colour:

skin colour: the coloring of a person's face
coloring: a visual attribute of things that results from the light they emit or transmit or reflect

Other hypernyms of skin colour include color, colour, colouring.

skin colour (noun)	coloring (noun)
the coloring of a person's face	the act or process of changing the color of something
	a visual attribute of things that results from the light they emit or transmit or reflect
	a digestible substance used to give color to food