approver vs authority

approver and authority both are nouns.

Word	Noun	Adjective	Verb	Adverb
approver	Yes	No	No	No
authority	Yes	No	No	No

As nouns, authority is a hypernym of approver; that is, authority is a word with a broader meaning than approver:

approver: an authority with power to approve
authority: (usually plural) persons who exercise (administrative) control over others

approver (noun)	authority (noun)
an authority with power to approve	the power or right to give orders or make decisions
	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