The molds for the two kits are identical. There may, however, be some differences between them. I haven't bought either of them in many years, but I can pass on some comments that have come up before here in the Forum.
In various threads over the past few years there have been complaints about Revell Germany's quality control. Modelers have encountered serious problems with warped parts, flash, broken parts (belaying pins are particularly delicate - but lots of modelers replace them with brass aftermarket parts anyway), and soft, flexible plastic - which can be a real problem in a kit like this.
Revell-Monogram, the US equivalent, has had more than its share of quality-control problems in the past few years as well, but the general consensus seems to be that the American kits are made of somewhat better plastic. I believe I also read that the latest kits in American Revell-Monogram boxes are in fact produced at a plant in China, which supposedly has better quality control.
The bottom line, unfortunately, is that this is a 40-year-old kit. It's a classic - one of the finest plastic sailing ship kit ever. But its age is inevitably going to have some consequences for the modeler.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.