Postal Money Order versus Bank Money Order ???

No one has said this yet, BANK money orders cost up to
$5.00 and have a limit of up to $300 total.
POSTAL money orders have a limit of up
to $1000 and cost $.90 - $1.25 ALOT cheaper.

USPS money orders are valid only within the U.S.

In favor of bank cashiers' checks, I recently sent one in payment for an overseas item, and the airmailed check never arrived. My bank was able to determine immediately whether the check had been cashed (had not been), placed a cancel payment on the check, and will return the money to my account. If the check had been cashed with a falsified signature, the money could probably have been recovered by arbitration between the issuing and paying banks. At least you get your $5 worth when it counts.

Bank money orders vary depending on the bank. My bank will cut me a money order for up to 1000 dollars. I've done this numerous times. After that, you have to either get more than one, or use a cashier's check. I don't get charged for any of them.

The USPS has 2 types of money orders, Domestic and International. They also have a limitation what countries the IMO's could be accepted at. For instance they won't issue one to Hong Kong and for the United Kingdom they only accept the US Domestic ones. These are my experiences as I always paid with these.

My banker told me it is possible to stop a certified check.