keep vs keep up

keep is a noun but keep up is not a noun.

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

As verbs, keep up is a hyponym of keep; that is, keep up is a word with a more specific, narrower meaning than keep:

Other hyponyms of keep include conserve, maintain, preserve.

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

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

Other hypernyms of keep include prolong, sustain.

keep (noun)	keep up (noun)
the main tower within the walls of a medieval castle or fortress
a cell in a jail or prison
the financial means whereby one lives

keep (verb)	keep up (verb)
prevent (food) from rotting	prevent from going to bed at night
prevent the action or expression of	keep informed
stick to correctly or closely	maintain a required pace or level
maintain by writing regular records	keep in safety and protect from harm, decay, loss, or destruction
supply with necessities and support	lengthen or extend in duration or space
hold and prevent from leaving
retain possession of
look after; be the keeper of; have charge of
retain rights to
maintain for use and service
have as a supply
store or keep customarily
stop (someone or something) from doing something or being in a certain state
allow to remain in a place or position or maintain a property or feature
conform one's action or practice to
behave as expected during of holidays or rites
cause to continue in a certain state, position, or activity
supply with room and board
maintain in safety from injury, harm, or danger
fail to spoil or rot
continue a certain state, condition, or activity
to rear