Simply put, ammunition that is loaded to a higher pressure to achieve more velocity.
If you mean +P, the difference is velocity.
A pistol rated to fire .38 +P ammunition is still going to be a .38 Special pistol, and can use regular .38 Special ammunition. .357 Magnum revolvers are also capable of chambering and firing .38 Special loads - regular, +P, and +P+ included.
A ".38 +P revolver" is simply a .38 Special revolver which is rated to fire +P loads. It's still a .38 Special, and the +P doesn't change the dimensions of the round itself.
you can shoot standard 38 special rounds out of a firearm marked for 38 special +p
You can use 38 special.
Yes it can. I do not think you will exceed the .357 pressures with .38 +P.
It's a .38 Special revolver. +P applies to the cartridge, and indicates a more powerful load than a standard round of the calibre. In this case, it would be a .38 S&W Special with a +P loading, hence .38 Special +P. You can fire regular .38 S&W Special cartridges through it. Whether or not it can fire +P or +P+ ammo, you need to read the instruction manual and find the manufacturer's information on this.
Contact the manufacturer for a correct answer
You need to contact Colt for a correct answer.
It depends on how old it is. Needs to be examined by a gunsmith.
The .38 Smith & Wesson cartridge was created in 1876. It is a shorter, fatter, less powerful cartridge than the .38 Smith & Wesson Special, created in 1899 (they cannot be interchanged). The .38 Special +P is a .38 Special cartridge that is loaded to 10% higher energy than a standard .38 Special. The .357 Magnum is a longer version of the .38 Special that is loaded to MUCH higher energy than a .38 Special +P.