the main difference is the layout of the motor. The rotor and stator are placed radial or axial to each other. See: http://machinedesign.com/motorsdrives/difference-between-ac-induction-permanent-magnet-and-servomotor-technologies for an example of a radial motor.
See: http://www.electric-vehiclenews.com/2010/03/australian-wheel-motor-company-prepares.html for an example of axial motor.