Although classical and flamencos share the same background, their modern incarnations have some important differences!
Classical guitars require a buzz-free tone that is only achieved by slightly higher action and some relief in the neck. Some concert players even prefer a much higher set-up to accommodate this buzz-free tone at the expense of easy playability. Classical guitars generally have either a cedar or spruce top, with practically any type of back/side combination.
On the other hand, flamenco guitars emphasize a much easier and faster playability, which is made possible by lowered action with almost no neck relief. This set-up leads to a buzz that classical players abhor, but which flamenco players adore! In fact, a strong “growl” from a flamenco guitar is often essential to replicating the blistering strumming patterns called “rasgueados” and rapid fire finger-picking called “picados” characteristic of the flamenco sound. Traditionally, flamenco guitars are built with a spruce top and cypress back and sides to achieve bright and vibrant tones. “Negra” guitars (i.e. a flamenco using non-cypress/sycamore back sides) have become more popular in recent years as well, and the choice between a great “blanca” and “negra” is largely up to a player’s tone preferences.