piece vs unit

piece and unit both are nouns.

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

piece (noun)	unit (noun)
a separate part of a whole	an assemblage of parts that is regarded as a single entity
game equipment consisting of an object used in playing certain board games	a single undivided whole
a portable gun	an organization regarded as part of a larger social group
a work of art of some artistic value	a single undivided natural thing occurring in the composition of something else
an item that is an instance of some type	any division of quantity accepted as a standard of measurement or exchange
a distance	an individual or group or structure or other entity regarded as a structural or functional constituent of a whole
a musical work that has been created
an artistic or literary composition
an instance of some kind
a serving that has been cut from a larger portion
a portion of a natural object
a share of something
a period of indeterminate length (usually short) marked by some action or condition

piece (verb)	unit (verb)
repair by adding pieces
eat intermittently; take small bites of
join during spinning
to join or unite the pieces of
create by putting components or members together