potentate vs tyrant

potentate and tyrant both are nouns.

Word	Noun	Adjective	Verb	Adverb
potentate	Yes	No	No	No
tyrant	Yes	No	No	No

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

Other hyponyms of potentate include shogun, strongman, autocrat, despot.

potentate (noun)	tyrant (noun)
a ruler who is unconstrained by law	a cruel and oppressive dictator
	any person who exercises power in a cruel way
	in ancient Greece, a ruler who had seized power without legal right to it