indulgence vs excess

indulgence and excess both are nouns.

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

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

Other hyponyms of indulgence include intemperance, intemperateness, self-indulgence, overindulgence, binge, orgy, splurge.

indulgence (noun)	excess (noun)
the act of indulging or gratifying a desire	excessive indulgence
foolish or senseless behavior	immoderation as a consequence of going beyond sufficient or permitted limits
the remission by the pope of the temporal punishment in purgatory that is still due for sins even after absolution	a quantity much larger than is needed
an inability to resist the gratification of whims and desires	the state of being more than full
a disposition to yield to the wishes of someone

indulgence (adjective)	excess (adjective)
	more than is needed, desired, or required