cabby vs hack-driver

cabby and hack-driver both are nouns.

Word	Noun	Adjective	Verb	Adverb
cabby	Yes	No	No	No
hack-driver	Yes	No	No	No

As nouns, cabby and hack-driver are synonyms defined as:

Other synonyms of cabby include cabdriver, cabman, hack driver, livery driver, taxidriver, taximan.

cabby (noun)	hack-driver (noun)
someone who drives a taxi for a living	someone who drives a taxi for a living