Galaxy Watch Serial numbers

Where do I find a description of the differences between different serial numbers. Specifically, for Galaxy Watch 4, what is the difference between SM-R865FZSAEUD vs SM-R865FZSAEUB.

In other words, what is the meaning of the last letter “D” vs “B”?


Samsung doesn’t have any description of the software versions that I can find. When doing a simple google search it looks like it is just the region where it sold. Most countries may have slight variations in regulations.

Samsung Developer Relations