postal order vs money order

postal order and money order both are nouns.

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

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

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

postal order (noun)	money 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