unit vs den

unit and den both are nouns.

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

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

unit (noun)	den (noun)
an assemblage of parts that is regarded as a single entity	a room that is comfortable and secluded
a single undivided whole	a unit of 8 to 10 cub scouts
an organization regarded as part of a larger social group	the habitation of wild animals
a single undivided natural thing occurring in the composition of something else	a hiding place; usually a remote place used by outlaws
any division of quantity accepted as a standard of measurement or exchange
an individual or group or structure or other entity regarded as a structural or functional constituent of a whole