mail carrier vs postman

mail carrier and postman both are nouns.

Word	Noun	Adjective	Verb	Adverb
mail carrier	Yes	No	No	No
postman	Yes	No	No	No

As nouns, mail carrier and postman are synonyms defined as:

Other synonyms of mail carrier include carrier, letter carrier, mailman.

mail carrier (noun)	postman (noun)
a man who delivers the mail	a man who delivers the mail