racer vs race driver

racer and race driver both are nouns.

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

As nouns, racer and race driver are synonyms defined as:

Other synonyms of racer include automobile driver.

racer (noun)	race driver (noun)
an animal that races	someone who drives racing cars at high speeds
slender fast-moving North American snakes
a fast car that competes in races
someone who drives racing cars at high speeds