driver vs owner-driver

driver and owner-driver both are nouns.

Word	Noun	Adjective	Verb	Adverb
driver	Yes	No	No	No
owner-driver	Yes	No	No	No

As nouns, owner-driver is a hyponym of driver; that is, owner-driver is a word with a more specific, narrower meaning than driver:

driver (noun)	owner-driver (noun)
a golf club (a wood) with a near vertical face that is used for hitting long shots from the tee	a motorist who owns the car that he/she drives
(computer science) a program that determines how a computer will communicate with a peripheral device
the operator of a motor vehicle
a golfer who hits the golf ball with a driver
someone who drives animals that pull a vehicle