classical music :) all classical guitars are just the plain ol' nylon string guitar. it's usually used for learners and some bands prefer the classical guitar because it gives a lovely mellow sound.
The term acoustic guitar in general do not refer to classical guitar. A typical guitar has narrower neck and steel string, classical guitar has wider neck and nylon string
It all depends on how much your going to spend people use rosewood spruis wood, most common acoustics like from Yamaha are made from maple and a thin plywood.