Excavators are used in many roles: An excavator is an engineering vehical consisting or a backhoe and cab mounted on a pivot (turntable is a more apt description) a top an undercarage with tracks or wheels.
Backhoe is a piece of excavating equipment consisting of a digging bucket on the end of an articulated arm, also called a stick or dipper.
Modern backhoes are powered by hydraulics. Backhoes gets its name because it is typically mounted on the back of a tractor or front loader. (Similar attachments for skid loaders are still called backhoes even though they are mounted on the front of the vehicle.
Note: the term excavator is sometimes used as a general term for any piece of digging equipment. Tracked excavators are sometimes called trackhoes.
