food colour vs food coloring

food colour and food coloring both are nouns.

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

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

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

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

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