It’s all about their license, which is what makes them professional
drivers and non-professional drivers. Professional drivers have to
get a special license, called a commercial driver’s license (CDL)
instead of the standard license, which lets them operate personal
use vehicles (cars and trucks).
It’s for this reason that professional drivers are sometimes called
“commercial drivers” since the licenses they hold are for
commercial vehicles or vehicles with a certain purpose: delivery
trucks, cars for delivering heavy cargo, or cars for people. Aside
from that, there are also vehicles for transporting hazardous
materials.
But professional drivers can also drive their own cars, not just
commercial ones. It’s because they already have a standard
license before applying for a business license (CDL), and that’s
what they had to do to get that license.
SOURCE: siempreauto.com