Cement, concrete, and mortar are three different materials. The basic difference is that cement is a fine binding powder (which is never used alone), mortar is composed of cement and sand, and concrete is composed of cement, sand, and gravel.
NOTE: If installing a snow melt mat embedded in cement/concrete, be sure to use 3/4“ or smaller aggregate in the concrete, as the openings in the mat are 1-¼“x 1-¼“.