POB vs call box

POB and call box both are nouns.

Word	Noun	Adjective	Verb	Adverb
POB	Yes	No	No	No
call box	Yes	No	No	No

As nouns, POB and call box are synonyms defined as:

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

Other synonyms of POB include letter box, PO Box, Post-Office box.

POB (noun)	call box (noun)
a numbered compartment in a post office where mail is put to be called for	booth for using a telephone
	a numbered compartment in a post office where mail is put to be called for