empire vs monarchy

empire and monarchy both are nouns.

Word	Noun	Adjective	Verb	Adverb
empire	Yes	No	No	No
monarchy	Yes	No	No	No

As nouns, monarchy is a hypernym of empire; that is, monarchy is a word with a broader meaning than empire:

empire: a monarchy with an emperor as head of state
monarchy: an autocracy governed by a monarch who usually inherits the authority

empire (noun)	monarchy (noun)
a monarchy with an emperor as head of state	an autocracy governed by a monarch who usually inherits the authority
a group of countries under a single authority
a group of diverse companies under common ownership and run as a single organization
the domain ruled by an emperor or empress; the region over which imperial dominion is exercised