ORIGINAL: Iturnright
Anyway, brushless motors are also different and better than brushed motors because there is no physical contact between the brushes as a brushed motor has. Therefore effieciency is increased as well as a reduction in wear and tear by not having two parts touch during the revolutions.
In brushless motors, the losses of a commutator and brushes are replaced by losses in the ESC. If you think that there are no losses there, feel how warm your ESC gets during use.
Most brushed motors are cheap can motors with reletively weak ferrite field magnets. Most brushless motors use super strong neodymiun alloy field magnets. The high magnetic field strength means that fewer turns of wire are needed to arrive at a given kV rating. Fewer turns means that there is room for a larger wire in the armature (stator). A larger diameter and shorter wire means a dramatically lower winding resistance and this is where both the high power and motor efficiency comes from.
Before brushless technology was introduced, Astroflite made premium brushed motors with high strength field magnets. These had power and efficiencys that compare with today's better brushless motors.