city district vs dominion

city district and dominion both are nouns.

Word	Noun	Adjective	Verb	Adverb
city district	Yes	No	No	No
dominion	Yes	No	No	No

As nouns, dominion is a hypernym of city district; that is, dominion is a word with a broader meaning than city district:

Other hypernyms of city district include district, territorial dominion, territory.

city district (noun)	dominion (noun)
a district of a town or city	a region marked off for administrative or other purposes
	dominance or power through legal authority