division vs naval unit

division and naval unit both are nouns.

Word	Noun	Adjective	Verb	Adverb
division	Yes	No	No	No
naval unit	Yes	No	No	No

As nouns, naval unit is a hypernym of division; that is, naval unit is a word with a broader meaning than division:

division (noun)	naval unit (noun)
the act or process of dividing	a military unit that is part of a navy
an arithmetic operation that is the inverse of multiplication; the quotient of two numbers is computed
the act of dividing or partitioning; separation by the creation of a boundary that divides or keeps apart
one of the portions into which something is regarded as divided and which together constitute a whole
discord that splits a group
an army unit large enough to sustain combat
a group of ships of similar type
a unit of the United States Air Force usually comprising two or more wings
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