one-man rule vs autocracy

one-man rule and autocracy both are nouns.

Word	Noun	Adjective	Verb	Adverb
one-man rule	Yes	No	No	No
autocracy	Yes	No	No	No

As nouns, autocracy is a hypernym of one-man rule; that is, autocracy is a word with a broader meaning than one-man rule:

one-man rule: a form of government in which the ruler is an absolute dictator (not restricted by a constitution or laws or opposition etc.)
autocracy: a political system governed by a single individual

Other hypernyms of one-man rule include autarchy.

one-man rule (noun)	autocracy (noun)
a form of government in which the ruler is an absolute dictator (not restricted by a constitution or laws or opposition etc.)	a political theory favoring unlimited authority by a single individual
	a political system governed by a single individual