Strings, when strummed, will produce sound waves as they vibrate. How loud and how far, as well as the tone, depends on how well the instrument itself can distribute those sound waves.
Acoustic guitars are hollow-bodied. The sound waves will travel out from the strings in all directions, but the loudest come from those that travel into the chamber of the instrument and reverberate back out through the sound hole. It's the principle of acoustics. Music halls are designed specifically to carry sound in the best way possible. The type of wood used in a guitar is just one factor in producing tone, but one of the more important ones.
Most electric guitars have solid bodies. You can hear the strings being strummed or plucked, but not well. They rely on electronic sensors called pickups - to 'pick up' the sound waves and recreate them electronically to be sent through a wiring to an amplifier. Additional electronics can create a whole variety of tones, as can amplifiers and other electronic equipment that usually is controlled by a foot pedal. Fuzz, flangers, phasers, distortion etc.
Semi-hollow bodied electrics do sound closer to an acoustic, and there are acoustic-electrics that act very much like an acoustic, with a pickup and sound that is sent through an amplifier as well as naturally.
While you can get a whole variety of tones out of acoustic guitars, it is quite obvious when you are hearing one being played. Electric guitars can be made to sound like all sorts of other things.