postal code vs ZIP

postal code and ZIP both are nouns.

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

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

postal code and ZIP: 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 code.

postal code (noun)	ZIP (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