There are three different categories that require a person to obtain a commercial driver's licence. Categories A and B are differentiated by the number of vehicles and their combined weight. Category C is for drivers transporting 16 or more people or hazardous material, explains the Federal Motor Carrier Safety Administration.
A category A CDL is for drivers of vehicles with a combined weight of 26,001 pounds, inclusive of towed units weighing no more than 10,000 pounds. A driver needs a category B CDL for a single vehicle of 26,001 pounds or any such vehicle towing a vehicle that does not exceed 10,000 pounds. A category C CDL is for drivers of vehicles that do not fall under the definitions of A and B and is for the purpose of transporting 16 or more people, including the driver, or material that is hazardous, according to the Federal Motor Carrier Safety Administration.