driver vs racer

driver and racer both are nouns.

Word	Noun	Adjective	Verb	Adverb
driver	Yes	No	No	No
racer	Yes	No	No	No

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

driver (noun)	racer (noun)
a golf club (a wood) with a near vertical face that is used for hitting long shots from the tee	an animal that races
(computer science) a program that determines how a computer will communicate with a peripheral device	slender fast-moving North American snakes
the operator of a motor vehicle	a fast car that competes in races
a golfer who hits the golf ball with a driver	someone who drives racing cars at high speeds
someone who drives animals that pull a vehicle