keep up vs stay up

keep up and stay up both are verbs.

Word	Noun	Adjective	Verb	Adverb
keep up	No	No	Yes	No
stay up	No	No	Yes	No

keep up (verb)	stay up (verb)
prevent from going to bed at night	not go to bed
keep informed
maintain a required pace or level
keep in safety and protect from harm, decay, loss, or destruction
lengthen or extend in duration or space