Brushless vs Coreless

ref: http://www.rctech.net/forum/89282-post2.html

Coreless motors are similar to what we now use, the difference being that their windings are not wound around an iron core. This makes the armature much lighter, so they spool up a lot quicker. Coreless motors have brushes and commutators, and will work with normal speed controls.

Brushless motors do away with the brushes and commutator, they need special speed controls to handle the switching that is normally performed by the brushes and comm.