sovereignty vs self-government

sovereignty and self-government both are nouns.

Word	Noun	Adjective	Verb	Adverb
sovereignty	Yes	No	No	No
self-government	Yes	No	No	No

As nouns, self-government is a hypernym of sovereignty; that is, self-government is a word with a broader meaning than sovereignty:

Other hypernyms of sovereignty include self-determination, self-rule.

sovereignty (noun)	self-government (noun)
the authority of a state to govern another state	government of a political unit by its own people
government free from external control
royal authority; the dominion of a monarch