authority vs consultant

authority and consultant both are nouns.

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

As nouns, consultant is a hyponym of authority; that is, consultant is a word with a more specific, narrower meaning than authority:

authority (noun)	consultant (noun)
the power or right to give orders or make decisions	an expert who gives advice
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