postal card vs post card

postal card and post card both are nouns.

Word	Noun	Adjective	Verb	Adverb
postal card	Yes	No	No	No
post card	Yes	No	No	No

As nouns, postal card and post card are synonyms defined as:

postal card and post card: a card for sending messages by post without an envelope

Other synonyms of postal card include mailing-card, postcard.

postal card (noun)	post card (noun)
a card for sending messages by post without an envelope	a card for sending messages by post without an envelope