superfluous vs supererogatory

superfluous and supererogatory both are adjectives.

Word	Noun	Adjective	Verb	Adverb
superfluous	No	Yes	No	No
supererogatory	No	Yes	No	No

As adjectives, superfluous and supererogatory are synonyms defined as:

superfluous and supererogatory: more than is needed, desired, or required

Other synonyms of superfluous include excess, extra, redundant, spare, supernumerary, surplus.

superfluous (adjective)	supererogatory (adjective)
more than is needed, desired, or required	more than is needed, desired, or required
serving no useful purpose; having no excuse for being