self-indulgence vs indulgence

self-indulgence and indulgence both are nouns.

Word	Noun	Adjective	Verb	Adverb
self-indulgence	Yes	No	No	No
indulgence	Yes	No	No	No

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

self-indulgence: excess in action and immoderate indulgence of bodily appetites, especially in passion or indulgence
indulgence: the act of indulging or gratifying a desire

Other hypernyms of self-indulgence include humoring, humouring, indulging, pampering.

As nouns, self-indulgence and indulgence are synonyms defined as:

self-indulgence and indulgence: an inability to resist the gratification of whims and desires

self-indulgence (noun)	indulgence (noun)
excess in action and immoderate indulgence of bodily appetites, especially in passion or indulgence	the act of indulging or gratifying a desire
an inability to resist the gratification of whims and desires	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