Doesn't *quite* work that way . . .
The first two are a diameter in mm, the second two are a height in mm, and the / or - number is either the number of motor windings or just a model in that series (a hint at it's kv).
so . . . a diameter of what? a height of what? Depends on the manufacturer, but the common definition is diameter and height of the stator, although some use the can size (outer dimensions).
On the whole, it will give you an idea of the general size/shape of the motor, but again, on the whole, you'll have to look at the motor's specs to see if it's suitable
. . . on the whole. In some cases, the manufacturers, trying to capitalize on the success of others (Yay, competition!) will actually hold to a standard. this has been the case recently with the advent of the FPV Racer class quad. Effectively the hobbyists have found a great use for what used to be a marginal product line -- dinky motors for dinky indoor planes. Since that market exploded a bit (and now the sunnysky 2206 skyrocketed from ~$10 to sometimes ~$25 a motor) , centered on a particular motor or two, the other manufacturers sprung in with "me too" by selling their version, with the same designations.
In these cases, anything designated 2206, 2204, 1806 or 1804 will likely be nearly identical to other motors with the same numbers. In larger motors, sadly, all bets are off.
