.38 S&W is a caliber, the same as .40 S&W is. Though Smith and Wesson did sell ammo under their brand in the 1970s up through the early 80s (I think that was the cut off). The ammo was made by Fiochi and just sold under the Smith and Wesson name.
Remington, Winchester, and I think one or two other small makers still offer .38 S&W ammo. Large numbers of top break revolvers and even many with swing out cylinders were made in this chambering, plus UK service guns in .38/200 will use it.