postal code vs ZIP code

postal code and ZIP code both are nouns.

Word	Noun	Adjective	Verb	Adverb
postal code	Yes	No	No	No
ZIP code	Yes	No	No	No

As nouns, postal code and ZIP code are synonyms defined as:

postal code and ZIP code: a code of letters and digits added to a postal address to aid in the sorting of mail

Other synonyms of postal code include postcode, ZIP.

postal code (noun)	ZIP code (noun)
a code of letters and digits added to a postal address to aid in the sorting of mail	a code of letters and digits added to a postal address to aid in the sorting of mail