Charcoal Bengals come in a variety of colors. Charcoal Bengals tend to have a dark mask in the face (black line down the nose and under the eyes), and a dark cape (wide band of black or brown down the back). Being a charcoal can affect their overall coloring (which you will see with the charcoal browns)
Charcoal Brown are very dark in overall color. They tend to have black markings with a more silvery background color instead of the usual brown. Although sometimes they can have brown coloring mixed in as well.
Charcoal Mink are slightly darker in the body than regular Mink, and have a black face mask as seen in the photos below.
Charcoal SLP don't change much in the body for coloring from a typical SLP. The biggest difference is in the face, they have striking black mask as seen in the photos below.