organisation vs unit

organisation and unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
organisation	Yes	No	No	No
unit	Yes	No	No	No

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

organisation (noun)	unit (noun)
the act of organizing a business or an activity related to a business	an assemblage of parts that is regarded as a single entity
the activity or result of distributing or disposing persons or things properly or methodically	a single undivided whole
the act of forming or establishing something	an organization regarded as part of a larger social group
an ordered manner; orderliness by virtue of being methodical and well organized	a single undivided natural thing occurring in the composition of something else
an organized structure for arranging or classifying	any division of quantity accepted as a standard of measurement or exchange
a group of people who work together	an individual or group or structure or other entity regarded as a structural or functional constituent of a whole
the persons (or committees or departments etc.) who make up a body for the purpose of administering something