coloring vs food colouring

coloring and food colouring both are nouns.

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

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

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

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

coloring (noun)	food colouring (noun)
the act or process of changing the color of something	a digestible substance used to give color to food
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