Torque motor vs servo motor

What is the difference between a torque motor and a servo motor?

A servo motor is a kind of motor which gives high control over position, acceleration, and velocity, because of a sensor that provides a feedback signa. A torque motor can be fitted with, for instance, an encoder to provide this feedback signal, making it technically a servo motor. 

There are also differences between a conventional servo motor and a servo torque motor, however. The first difference is that conventional servo motors generally have a long axis, small diameter, and an output shaft, while a torque motor is toroid shaped causing it to have a bigger diameter and shorter axis. Moreover, servo motors generally have an added gearbox, while torque motors do not. The third difference is that torque motors are able to directly drive the application without any additional mechanics, while conventional servo motor are not. 

Conventional Servo motor
Torque Motor MI-250 frameless direct drive
Stator and Rotor of a Torque motor