What is 38 short ammo?

There are more than a dozen different .38 caliber cartridges. Most of them are obsolete- however, there are 2 that are still fairly common. The one that may be called a .38 Short (incorrectly, but they do get called that) is the .38 S&W. This is shorter and fatter than the .38 Special cartridge, and does not interchange with it.