A primary driver is the main driver of the vehicle that is being insured, and they will always be listed first on the insurance policy. ... When you apply for an auto insurance policy in the United States, the insurance agent or insurance broker will ask you which person drives the vehicle the most often?
A secondary driver is someone who regularly uses the vehicle, but doesn't use it the most. These drivers need to be added to the insurance policy for that vehicle. In practical terms, this is often a spouse who may be the primary driver of another vehicle but who might use your car from time to time.

Fleet driver - a driver who drives the vehicles of a car fleet