authority vs self-assurance

authority and self-assurance both are nouns.

Word	Noun	Adjective	Verb	Adverb
authority	Yes	No	No	No
self-assurance	Yes	No	No	No

As nouns, authority and self-assurance are synonyms defined as:

authority and self-assurance: freedom from doubt; belief in yourself and your abilities

Other synonyms of authority include assurance, confidence, self-confidence, sureness.

authority (noun)	self-assurance (noun)
the power or right to give orders or make decisions	freedom from doubt; belief in yourself and your abilities
official permission or approval
freedom from doubt; belief in yourself and your abilities
an authoritative written work
an administrative unit of government
an expert whose views are taken as definitive
(usually plural) persons who exercise (administrative) control over others