Chalkboard chalk is free of such binding agents, and can easily be wiped off of a chalkboard. Never use chalk on a chalkboard unless the manufacturer recommends it for chalkboard use.
Drawing chalk contains oils that act as a binder. Use drawing chalks on paper surfaces, and on sidewalks. They are not meant to be used on chalkboards. If they are used on a chalkboard, it may be difficult to remove all traces.
