subsistence vs sustenance

subsistence and sustenance both are nouns.

Word	Noun	Adjective	Verb	Adverb
subsistence	Yes	No	No	No
sustenance	Yes	No	No	No

As nouns, sustenance is a hypernym of subsistence; that is, sustenance is a word with a broader meaning than subsistence:

Other hypernyms of subsistence include bread and butter, keep, livelihood, living, support.

subsistence (noun)	sustenance (noun)
minimal (or marginal) resources for subsisting	the act of sustaining life by food or providing a means of subsistence
the state of existing in reality; having substance	a source of materials to nourish the body
a means of surviving	the financial means whereby one lives