Electric guitars have a few more bells and whistles than acoustics. Most electric guitars are not hollow, thus when you strike the strings, the sound produced is very quiet. In order to project the sound of an electric guitar, a guitar amplifier is needed. Generally, people find electric guitars to be a little more confusing than acoustic guitars - there are more knobs and buttons to deal with, and there are also a few more things that can go wrong.
Electric guitars are generally much easier to play than acoustic guitars. The strings are lighter, and easier to press down. The sore fingers that many novices experience when learning on an acoustic guitar generally aren't nearly as much of an issue when learning on electric guitar.
Electric guitars have a different role in music than acoustic guitars. Whereas acoustic guitars are often used to strum chords to many songs, electrics are used to play "guitar leads" as well as chords.