overindulgence vs indulgence

overindulgence and indulgence both are nouns.

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

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

Other hypernyms of overindulgence include humoring, humouring, indulging, pampering.

overindulgence (noun)	indulgence (noun)
excessive indulgence	the act of indulging or gratifying a desire
	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