keep on vs sustain

keep on and sustain both are verbs.

Word	Noun	Adjective	Verb	Adverb
keep on	No	No	Yes	No
sustain	No	No	Yes	No

As verbs, sustain is a hypernym of keep on; that is, sustain is a word with a broader meaning than keep on:

keep on: allow to remain in a place or position or maintain a property or feature
sustain: lengthen or extend in duration or space

Other hypernyms of keep on include keep up, prolong.

keep on (verb)	sustain (verb)
allow to remain in a place or position or maintain a property or feature	undergo (as of injuries and illnesses)
	establish or strengthen as with new evidence or facts
	admit as valid
	supply with necessities and support
	provide with nourishment
	be the physical support of; carry the weight of
	lengthen or extend in duration or space