It's very difficult to give a definitive answer, because different cartridges have different specifications, and you will see different performance depending on the barrel length of the gun the bullet is fired from. One particular 9mm might be better than one particular .38, but not better than another. If you don't have other access to any type of ballistics chart, try an internet search for "handgun bullet ballistics chart" or something similar and see what you can find.
.001 inches. Makes a difference depending on what you are shooting, how old the barrel is, etc..
The .22 caliber bullet is ABOUT .22 inches wide. A .32 bullet is about .32 inches wide. The bullet will also be heavier due to size.
The .22 bullet is smaller than the 9mm in size, (about 6mm) and is lighter in weight.
metric vs inch measurement
Generally speaking, the .45 caliber bullet is larger in diameter and heavier than a 9mm bullet.
Size and amount of propellant
As far as diameter, there is very little difference. A .357 is .358 in diameter and a 9mm is .356 in diameter.
They are different ways of expressing the same thing. A bullet that is 7.65mm is just that- 7.65 millimeters in diameter. Is the US, we frequently use caliber rather than millimeters- that same bullet was be a .32 caliber- or 32/100ths of an inch in diameter.
Caliber refers to the diameter of a bullet (bullet is the part of a cartridge that is fired out of the gun). A .223 caliber bullet is .223 inches across. It is normally used as a rifle cartridge. a .45 caliber bullet is more than twice as wide as a .223, and is usually used in pistols. The .223 is lighter- it weighs about 1/4 of a .45 bullet, and they are different shapes- .223 is usually pointed, the .45 is rounded.
Size and relative power. A .40 caliber bullet is .40 of an inch and the entire cartridge is 28.8 millimeters long. A .50 caliber (handgun) bullet is .50 of an inch and the entire cartridge is 40.99 millimeters long. The .50 caliber has more powder, more velocity, and more muzzle energy.
There are various difference, but the most common answer would be the .45 is .05 of an inch larger in diameter than a .40.
The .40 caliber bullet is a little larger in diameter and is a little heavier (under most circumstances). The .40 will usually have more powder, velocity, and muzzle energy. Also, the .40 is designed for use in a semi-automatic and the .38 is a revolver cartridge.