sustentation vs upkeep

sustentation and upkeep both are nouns.

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

As nouns, sustentation and upkeep are synonyms defined as:

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

Other synonyms of sustentation include maintenance, sustainment, sustenance.

sustentation (noun)	upkeep (noun)
the act of sustaining life by food or providing a means of subsistence	activity involved in maintaining something in good working order
	the act of sustaining life by food or providing a means of subsistence