upkeep vs sustenance

upkeep and sustenance both are nouns.

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

As nouns, upkeep and sustenance are synonyms defined as:

upkeep and sustenance: the act of sustaining life by food or providing a means of subsistence

Other synonyms of upkeep include maintenance, sustainment, sustentation.

upkeep (noun)	sustenance (noun)
activity involved in maintaining something in good working order	the act of sustaining life by food or providing a means of subsistence
the act of sustaining life by food or providing a means of subsistence	a source of materials to nourish the body
	the financial means whereby one lives