hold back vs keep

hold back is not a noun while keep is a noun.

Word	Noun	Adjective	Verb	Adverb
hold back	No	No	Yes	No
keep	Yes	No	Yes	No

As verbs, hold back and keep are synonyms defined as:

Other synonyms of hold back include keep back, restrain.

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

Other hypernyms of hold back include hold on.

hold back (noun)	keep (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

hold back (verb)	keep (verb)
prevent the action or expression of	prevent (food) from rotting
hold back, as of a danger or an enemy; check the expansion or influence of	prevent the action or expression of
hold back; keep from being perceived by others	stick to correctly or closely
secure and keep for possible future use or application	maintain by writing regular records
wait before acting	supply with necessities and support
refrain from doing	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