sovereign vs supreme

sovereign is a noun but supreme is not a noun.

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

As adjectives, sovereign and supreme are synonyms defined as:

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

sovereign (adjective)	supreme (adjective)
greatest in status or authority or power	greatest in status or authority or power
(of political bodies) not controlled by outside forces	greatest or maximal in degree; extreme
	highest in excellence or achievement
	final or last in your life or progress