colours vs ensign

colours and ensign both are nouns.

Word	Noun	Adjective	Verb	Adverb
colours	Yes	No	No	No
ensign	Yes	No	No	No

As nouns, ensign is a hyponym of colours; that is, ensign is a word with a more specific, narrower meaning than colours:

colours (noun)	ensign (noun)
a flag that shows its nationality	colors flown by a ship to show its nationality
a distinguishing emblem	an emblem flown as a symbol of nationality
	a person who holds a commissioned rank in the United States Navy or the United States Coast Guard; below lieutenant junior grade