The meaning of color and colour is the same thing. The word color is the American English spelling, while colour is the British English spelling. Both color and colour mean tint or paint. The adjective of colour is coloured. The adverb of color is colored. For example, “Jenny likes the color green” Green is the adjective that describes the color. With the sentence, “The rainbow has many different colors,” the word color is a noun.
The word color possesses its adjectival form, and in the word colorful, it is in an adverbial way. Since color is the appropriate American spelling of the word, whenever you type the word colour in MS word, it will be underlined with a red line, which demonstrates that the word is spelled wrong, and this is because Microsoft is an American company. The language in MS word is American English.