food coloring vs food colour

food coloring and food colour both are nouns.

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

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

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

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

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