I asked my boyfriend about this and he said that the difference was the way the motor is made. With indication motors the smoke that the motor uses to run is all in one circit but in the other motors the smoke has to jump from pole to pole and until it heats up enough the smoke makes a buzzing sound due to friction with the air. That's also why those motors do not last as long as the indication motors as a little of the smoke can leak out each time until it no longer has enough smoke for it to run.
Is that like the phrase convertion thats needed to go from alternative currant to direct currant? I tried to get that link but my computer told me I needed to get something else to read it and all the shops are shut right now. Will I be able to get it from PC World?