sustainment vs sustentation

sustainment and sustentation both are nouns.

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

As nouns, sustainment and sustentation are synonyms defined as:

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

Other synonyms of sustainment include maintenance, sustenance, upkeep.

sustainment (noun)	sustentation (noun)
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