Not exactly, it's going to get pretty technical, lemme know for any clarity.
'Turns' is the number of times a copper wire is wound around the armature of a motor. The armature is the part inside a motor that spins. The higher the turn number, the more windings. However, the higher windings means that thinner and thinner copper wire has to be used and thus less power.
Additionally, there are two basic types of motors, 'stock' and 'modified'. A stock motor is basically what it means, and doesn't have like upgrades magents etc and stock motors usually are either 27 turn or 19 turn. Modified motors and run anywhere from 27 down to 5 or 6 turn, I think. Of course the lower the turn, the more power, and the more it will suck battery life. I have a 6 turn, and that thing is crazy fast, but will only get 2-3 mins max.
One more thing would be, in R/C speak, motors will always mean electric motors, and engines will always nitro or gasoline engines. .21 (point 21) is a common sized engine for 1/8th.