Pictures would help.
From the markings you quote, it might even be a cheap Spanish copy of a S&W revolver. If that's correct, it may not be safe to shoot.
S&W made lots of revolvers to fit each kind of cartridge, but never made any to fit both. It wouldn't've been safe.
The .38 S&W cartridge is both shorter and larger in diameter than is the .38 Special. But if the pistol's cylinder is just barely long enough, and if it has been bored straight through rather than having been chambered for a specific cartridge, then .38 Special rounds will slide easily into the chambers of a .38 S&W cylinder. However, if you fire .38 Special cartridges in a bored-through .38 S&W chamber, you are just asking for a very destructive "KABOOM!" because the .38 Special is a more powerful round than is the .38 S&W.
Pictures. We need pictures. Make sure to show all of the markings on the gun, including inside the space in the frame into which the cylinder's "crane" fits.