PO vs P.O.

PO and P.O. both are nouns.

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

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

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

Other synonyms of PO include petty officer.

PO (noun)	P.O. (noun)
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
a noncommissioned officer in the Navy or Coast Guard with a rank comparable to sergeant in the Army