Charcoal pencils are basically compressed charcoal, but the timber casing keeps your hands clean, and they are easy to sharpen for fine work. However, they wear out quickly if you are shading big areas.
Carbone pencils are made from an oiler, sooty carbon that gives rich blacks like charcoal but without the dust. They smear a little but don't smudge and are dustless, so are good for sketchbooks or when you don't want to use fixative.
Check out my Charcoal for Drawing Top Picks for more information.