Federal Postal Note & Scrip Stamps

Federal Postal Note & Scrip Stamps were used on money orders.  There were three issues of these.  The first issue including van Dam FPS15, 16, 18, 19, 21 and 22 were  inscribed "Postal Scrip".  All other stamps in this issue and the remaining issues were inscribed "Postal Note".  The designs were the same in all issues.  The only way to tell them apart is by measuring the stamp's design from the outside of the framelines.