No- two different cartridges. They are for different guns and do not interchange. The 9x19 is also the 9mm Parabellum or 9mm Luger- the 9x18 is the 9mm Makarov.
No. Most 9mm pistols are fitted for 9x19 rounds, but a few use 9x21mm. or 9x17, or 9x18, or 9x20
Assuming you mean 9mm, and not calibre, you have a number of options. There's the 9x19 Parabellum/Luger, the 9x17 (more commonly known as the .380 ACP in the US), the 9x18 Makarov, the 9x21, the 9x23 Steyr, 9x23 Winchester, 9x25 Mauser 'Export', 9x25 Dillon... quite a variety to choose from. Most likely, you'd be referring to a 9x19 firearm (also known as 9mm Luger or Parabellum).
Different makers. The cartridge used is the 9x19.
There is no exact match to the 9x18 MAK round, but if you are handy with reloading equipment, it is possible to shave down a 9x19 casing to function properly.
9x19, also known as the 9mm Luger or 9mm Parabellum.
.380 ACP is 9x17mm, while the 9mm Parabellum/Luger is 9x19mm. Additionally, the 9x19 uses heavier projectiles, and also generates higher chamber pressure, necessitating a locked breech pistol, whereas most .380/9x17 pistols use an unlocked breech.
There is no difference- Luger is a name that is commonly used in America and Parabelum is used in Europe, they are both 9x19.
The .380 ACP is a type of 9mm... 9x17, and is sometime referred to as the 9mm Short or 9mm Kurz. It is NOT the same as the 9mm Luger/Parabellum (9x19), and it is NOT compatible with any other type of 9mm cartridge (such as the 9x19 Luger/Parabellum, 9x18 Makarov, 9x21, 9x23, 9x25, etc.).
NO- outside of case dimensions, the 9x18 uses a .366 bullet designed for the Makarov. The standard international cartridge, 9mm Luger (9x19) uses a .355 bullet. The Luger will not fit in the Makarov, and if you try to fire the Makarov in a standard 9mm gun, you may just damage the gun or blow out the barrel
There are about a dozen cartridges that have 9mm as part of their name. If you mean the 9mm Parabellum (sometimes called 9mm Luger) it is longer than the Makarov, not as fat, and has more power. The 9mm Makarov is actually 9.27 mm.
A bullet with a diameter of approximately 9mm. Not all 9mm projectiles are exactly 9mm in diameter - the 9x19 Parabellum/Luger has a diameter of 9mm, while the 9x18 Makarov has a diameter of 9.27mm, the 9x23 Steyr has a diameter of 9.03mm, etc.