DC motors and DC gear motors are both widely used in smaller appliances, toys, automobiles, cycles and low voltage applications as their speed can be varied, easily and their torque can be increased, again, simply, by using gears / gear boxes.
A DC Gear Motor is normally thought of as a one piece unit, a DC motor with the shaft into the front housing which holds a set of gears for a specific output speed and torque needs.
In construction a DC gear motor differ from normal motor by having a inbuilt assembly of gears within the frame. Gear assembly comes as extended assembly and the gear ratio is set for the desired speed reduction.
On the outlook normal motors have shaft at the centre whereas in geared motors the external shaft is below the centre portion.
In normal motors speed reduction is achieved by armature voltage control method and corresponding to reduction of speed the output power delivery also get reduced.
On the other hand geared motors offer torque amplification. Corresponding to reduction of speed obtained by the gear ratio torque delivered is amplified since power transferred as output is more or less same as power delivered by the motor, the difference being small amount of power loss occuring in gear wheels.
