For the heck of it, I ran a .38 S&W case through a .38 Spl die. The rims are identical, and I use the same cast bullets in my Colt .38 S&W and Smith and Wesson .38 Airweight. The .38 S&W case sized down perfectly (and easily) to fit in the Airweight.
Would the sized .38 S&W case be useable in the .38 Spl, as a .38 Short? I feel like I'm missing something.
.357 to .38
.9mm to .380 (9mm Kurz)