indulgence vs gratification

indulgence and gratification both are nouns.

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

As nouns, gratification is a hypernym of indulgence; that is, gratification is a word with a broader meaning than indulgence:

indulgence (noun)	gratification (noun)
the act of indulging or gratifying a desire	the act or an instance of satisfying
foolish or senseless behavior	state of being gratified or satisfied
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