What's the difference between analog and digital sound?

We could write a book about that. When you watch a movie - you are seeing approximately 30 still pictures per second. Your eyes are fooled into seeing a continuous image. However, you can always tell the difference between the real thing and a movie of the real thing. This is similar to digital audio, where sound is chopped up into samples (instantaneous numerical representations of the strength of a sound). When the samples are reassembled by digital to analog converters, a sound can be heard as a representation of the original sound - today with quite good results. In an analog musical circuit, the electrons move analogously to the sound you hear - just as a guitar string vibrates - ultimately to produce the sound you hear. The big deal about this is in specialized applications, such as an electronic musical instruments or amplifiers - where the musician interacts closely with the sound and feel of an instrument. Analog instruments have a particular sound and feel that hasn't been duplicated and is MUSICALLY DESIRABLE.