money order vs postal order

money order and postal order both are nouns.

Word	Noun	Adjective	Verb	Adverb
money order	Yes	No	No	No
postal order	Yes	No	No	No

As nouns, money order and postal order are synonyms defined as:

money order and postal order: a written order for the payment of a sum to a named individual; obtainable and payable at a post office

money order (noun)	postal order (noun)
a written order for the payment of a sum to a named individual; obtainable and payable at a post office	a written order for the payment of a sum to a named individual; obtainable and payable at a post office