What is the difference between a drumlin and an esker?

Although drumlins and eskers are both hilly glacial landforms, they differ in shape. Eskers are narrow, long, winding hills that were deposited by streams underneath the glaciers. Drumlins, in contrast, are oval egg-like hills featuring a steep slope at one end and a gentle incline at the other.

There is no firm conclusion on what glacial force causes drumlins, though the reigning hypothesis suggests that the bulldozing-like glacial movement pushes loose gravel material into a gentle mound. Drumlins typically appear in swarms of hills, all oriented in the same direction. Theory suggests that this orientation is lined up with the movement of the glaciers.