An acoustic eletric (or electro-acoustic as they're better known) is just an acoustic guitar which has an in-build pickup or microphone. As already mentioned, it just means you can plug it into an amplifer or PA to allow you and the audience to hear it betterr in live situations. The advantage of an electro-acoustic is it makes life easier when gigging.

Whilst you can put it through an amplifer with distortion, I think its unlikely to sound like an genuine electric without several effects placed upon it first - and even then there will be noticable differences in tone, etc.

Again, like penny's said, acoustics tend to be a little harder to play to begin with (although this isn't always the case!) because they tend to have a slightly higher action than an electric. I personally would advise learning on an acoustic (or electro-acoustic) as it helps build up finger strength and can often make playing an electric feel much lighter and easier.

Ultimately though, like everything, it's a matter of preference and what you actually want to play.

Hope that's of some use!