9mm Luger, 9mm Parabellum, 9mm NATO, 9x19mm... what's the difference between these cartridges? And what about all those other 9mm cartridges in the world - will they work in my 9mm pistol?
Now's as good a time as any to find out! Follow the link to read about it.

Comments
They all refer to the same cartridge. No difference.
The only difference is where you happen to be when you purchase this ammunition. I believe Europeans refer to it as 9MM Parabelum and in the U.S. it’s called 9mm Luger, or vice versa. As the other Post says, they are one and the same.
9×19 mm.
It might be worth reading this: http://gunnuts.net/2009/04/03/9mm-nato-vs-9mm-luger/
The NATO load is heavier and has higher pressure.