[atoav]

As a guitarist who plays both classical and electrical guitar, I must say that I side with the theory that both instruments are more different than they are alike.

Sure, you can play more or less the same things on both instruments, and anybody who plays electrical will be able to do something on an acoustic guitar and vice versa. But anybody who plays acoustic guitar will also be able to do something on a lute, a mandolin or heck even on a double bass. You will also be able to use your guitar to sound like an organ, a flute, or a synthesizer, with sufficient effect pedals.

For me what makes an instrument is the music it lends itself easily. Give a five year old who never played before an acoustic guitar with fresh strings and an electric guitar plugged into an amp and they will do completely different things with it, because the instruments lend itself to different things. Ironically an electric guitar can be much more direct, because you will hear every slight tiny movement of your fingers amplified. An acoustic guitar (with fresh strings) can be extremely articulate, but you have to put in more energy to produce these sounds.

I certainly see the amplifier as part of the instrument with the electrical guitar, and that alone makes a ton of difference between the two.