food color vs food colour

food color and food colour both are nouns.

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

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

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

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

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