electric motors most often spark (grab your electric drill in the dark, pull the plug and wala! let there be light.
when electricity runs through a wire, it generates a magnetic field, "winding" the wire in a particular manner adds the fields together, and this field can push/pull a shaft. At some point a couple of conductors seat themselves on the spinning shaft and I think this is where the spark occurs. Generators work in reverse, a spinning magnet induces current in wires.
I think maybe these sparkless motors are purely using the magnetics to make a less efficient motor but one that doesn't spark.
It's been a good 6 years since I've seen the theory, so I may not be totally accurate, not my field.
you might try "howstuffworks.com", and look for electric motors, i love that site, good articles on engines, trannies, etc.