POB vs Post-Office box

POB and Post-Office box both are nouns.

Word	Noun	Adjective	Verb	Adverb
POB	Yes	No	No	No
Post-Office box	Yes	No	No	No

As nouns, POB and Post-Office box are synonyms defined as:

POB and Post-Office box: a numbered compartment in a post office where mail is put to be called for

Other synonyms of POB include call box, letter box, PO Box.

POB (noun)	Post-Office box (noun)
a numbered compartment in a post office where mail is put to be called for	a numbered compartment in a post office where mail is put to be called for