food colour vs colouring

food colour and colouring both are nouns.

Word	Noun	Adjective	Verb	Adverb
food colour	Yes	No	No	No
colouring	Yes	No	No	No

As nouns, food colour and colouring are synonyms defined as:

food colour and colouring: a digestible substance used to give color to food

Other synonyms of food colour include coloring, food color, food coloring, food colouring.

food colour (noun)	colouring (noun)
a digestible substance used to give color to food	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