reign vs dominion

reign and dominion both are nouns.

Word	Noun	Adjective	Verb	Adverb
reign	Yes	No	Yes	No
dominion	Yes	No	No	No

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

Other hypernyms of reign include rule.

reign (noun)	dominion (noun)
royal authority; the dominion of a monarch	a region marked off for administrative or other purposes
the period during which a monarch is sovereign	dominance or power through legal authority
a period during which something or somebody is dominant or powerful

reign (verb)	dominion (verb)
have sovereign power
be larger in number, quantity, power, status or importance