separation vs division

separation and division both are nouns.

Word	Noun	Adjective	Verb	Adverb
separation	Yes	No	No	No
division	Yes	No	No	No

As nouns, division is a hyponym of separation; that is, division is a word with a more specific, narrower meaning than separation:

separation (noun)	division (noun)
the social act of separating or parting company	the act or process of dividing
the act of dividing or disconnecting	an arithmetic operation that is the inverse of multiplication; the quotient of two numbers is computed
(law) the cessation of cohabitation of man and wife (either by mutual agreement or under a court order)	the act of dividing or partitioning; separation by the creation of a boundary that divides or keeps apart
sorting one thing from others	one of the portions into which something is regarded as divided and which together constitute a whole
the distance between things	discord that splits a group
coming apart	an army unit large enough to sustain combat
the termination of employment (by resignation or dismissal)	a group of ships of similar type
the space where a division or parting occurs	a unit of the United States Air Force usually comprising two or more wings
the state of lacking unity	an administrative unit in government or business
	(botany) taxonomic unit of plants corresponding to a phylum
	(biology) a group of organisms forming a subdivision of a larger category
	a league ranked by quality