ALOT. the diameter isn't the only thing to consider. although the calibers are close the 9mm and 38 special are no where near each other. a 9mm is usually 9 x 19mm and is 115-124 grains and a 38 special is approx. 9.07 x 39mm near 160 grains and obviously packs more of a punch. fire a 9mm and then a 38 special and it will make sense.
The .22 bullet is smaller than the 9mm in size, (about 6mm) and is lighter in weight.
Generally speaking, the .45 caliber bullet is larger in diameter and heavier than a 9mm bullet.
The 380 ACP, also known as the 9mm Short, 9x17, 9mm Browning, 9mm Kurz and 9mm Corto uses a .355 diameter bullet. The 38 special uses a .357 diameter bullet. Additionally, the 380 ACP is designed for a semi-automatic and the .38 special is designed for a revolver.
Glock is a brand. 9mm is a caliber size. So, there is no difference between a 9mm glock and a 9mm of another brand as far as caliber size.
As far as diameter, there is very little difference. A .357 is .358 in diameter and a 9mm is .356 in diameter.
The most basic answer is, a 9mm has a smaller diameter. Other differences, (in most cases) less muzzle energy, smaller and lighter bullet, higher velocity.
Yes
9mm = .355 40 cal = .40
No, the bullet will not seat.
9mm is roughly .35 caliber, .32 caliber is slightly smaller, 3 hundredths of an inch smaller, in diameter.
No
9 millimeter is the caliber. IMPROVING ANSWER: A "9mm" bullet is actually .355 or .356 of an inch in diameter. So the caliber is about .36, but nobody calls it that because it would be confusing. Everybody calls it a 9mm and if somebody asks you what "caliber" that pistol is, you can answer "It's a 9mm" without having to add or explain anything. further improve: 9mm is the correct answer. you can find the caliber by measuring the diameter of the bullet. translate to millimeters or inches and that's the caliber. 9mm is a 9mm caliber not "around .36"