An explanation. There are .38 S&W and .38 Special, two different cartridges.

The .38 S&W dates into the 1870's. In 1899 S&W designed a new cartridge which was designated .38 S&W Special which was a modification of the shorter .38 Long Colt (go figure). Colt adopted the .38 S&W Special shortly after but modified the bullet to a flat point and re-named the cartridge .38 Colt Special.

Both the .38 S&W Special and Colt Special cartridges were manufactured concurrently for many years, but the Colt loading fell out of currency somewhere around 1950. They were dimensionally and functionally identical so one was superfluous. Once the Colt loading was discontinued there was no longer a reason to try to maintain a distinction between the two, and the common terminology for the cartridge was simplified to just .38 Special.

S&W has always marked their guns .38 S&W Special since they were the originators of the cartridge. Every other manufacturer simply calls the cartridge the .38 Special.

In short, .38 S&W Special and plain .38 Special are the same thing. .38 S&W is a different cartridge which is both shorter and larger in case diameter than the .38 Special and is not interchangeable.