The terms "45 Colt" and "45 Long Colt" are often used interchangeably to refer to the same cartridge. However, there is a historical distinction between the two.

The cartridge in question was originally developed by Colt's Manufacturing Company in 1872 for their Single Action Army revolver, also known as the Colt Peacemaker. At that time, it was simply known as the ".45 Colt" or the ".45 Colt Revolver Cartridge."

Later, to differentiate it from a shorter version of the cartridge that was introduced for use in double-action revolvers, the term "45 Long Colt" emerged. This distinction was made to avoid confusion between the two versions of the cartridge.

However, it's important to note that the term "45 Long Colt" can be misleading because there is no shorter version of the cartridge called "45 Short Colt." The shorter version that prompted the distinction was actually called the ".45 Colt, Army Revolver," and it is no longer commonly used or produced.

In modern times, the term "45 Colt" is more commonly used to refer to the cartridge, while "45 Long Colt" is sometimes used by individuals to differentiate it from other .45 caliber cartridges, such as the .45 ACP (Automatic Colt Pistol).

To summarize, both "45 Colt" and "45 Long Colt" refer to the same cartridge. "45 Colt" is the more commonly used term today, while "45 Long Colt" emerged historically to differentiate it from a shorter version of the cartridge that is no longer in common usage.