P.O. vs PO

P.O. and PO both are nouns.

Word	Noun	Adjective	Verb	Adverb
P.O.	Yes	No	No	No
PO	Yes	No	No	No

As nouns, P.O. and PO are synonyms defined as:

P.O. and PO: a noncommissioned officer in the Navy or Coast Guard with a rank comparable to sergeant in the Army

Other synonyms of P.O. include petty officer.

P.O. (noun)	PO (noun)
a noncommissioned officer in the Navy or Coast Guard with a rank comparable to sergeant in the Army	an independent agency of the federal government responsible for mail delivery (and sometimes telecommunications) between individuals and businesses in the United States
	a noncommissioned officer in the Navy or Coast Guard with a rank comparable to sergeant in the Army