autonomous vs sovereign

autonomous is not a noun while sovereign is a noun.

Word	Noun	Adjective	Verb	Adverb
autonomous	No	Yes	No	No
sovereign	Yes	Yes	No	No

As adjectives, autonomous and sovereign are synonyms defined as:

autonomous and sovereign: (of political bodies) not controlled by outside forces

Other synonyms of autonomous include independent, self-governing.

autonomous (noun)	sovereign (noun)
	a nation's ruler or head of state usually by hereditary right

autonomous (adjective)	sovereign (adjective)
(of political bodies) not controlled by outside forces	greatest in status or authority or power
(of persons) free from external control and constraint in e.g. action and judgment	(of political bodies) not controlled by outside forces
existing as an independent entity