The electric piano comes in many forms and usually has a slightly smaller physical size and range then the acoustic piano but can have a multitude of different tones and effects depending on the make and model.
Essentially the electric, usually amplified version of the acoustic piano. The electric pianos exist in a variety of sizes from a full 88 key length (same as the acoustic piano) to as small as 49 keys with 88 and 76 being the most common. Many electric pianos have a sound bank of various piano emulations which can duplicate the sound of either an acoustic piano or other electrics.
A famous electric piano that rose to prominence in the 60's and 70's with bands like The Doors and Led Zeppelin and favored by jazz piano great Herbie Hancock. The Rhodes comes in various sizes with the most common being the 88 and 73 key models.
The piano heard on Stevie Wonder's classic track "Superstition". The clavinet is a unique sounding electric piano based on the clavichord and is used prominently in soul, jazz and r&b music. The clav usually has 60 keys and therefore has a slightly smaller range than the normal electric piano.