calling card vs phone card

calling card and phone card both are nouns.

Word	Noun	Adjective	Verb	Adverb
calling card	Yes	No	No	No
phone card	Yes	No	No	No

As nouns, calling card and phone card are synonyms defined as:

calling card and phone card: a card that is used instead of cash to make telephone calls

calling card (noun)	phone card (noun)
a distinguishing characteristic or behavior	a card that is used instead of cash to make telephone calls
a printed or written greeting that is left to indicate that you have visited
a card that is used instead of cash to make telephone calls