indulgence vs mishegaas

indulgence and mishegaas both are nouns.

Word	Noun	Adjective	Verb	Adverb
indulgence	Yes	No	No	No
mishegaas	Yes	No	No	No

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

Other hyponyms of indulgence include meshugaas, mishegoss, buffoonery, clowning, frivolity, harlequinade, japery, prank.

indulgence (noun)	mishegaas (noun)
the act of indulging or gratifying a desire	(Yiddish) craziness; senseless behavior or activity
foolish or senseless behavior
the remission by the pope of the temporal punishment in purgatory that is still due for sins even after absolution
an inability to resist the gratification of whims and desires
a disposition to yield to the wishes of someone