workman vs workingman

workman and workingman both are nouns.

Word	Noun	Adjective	Verb	Adverb
workman	Yes	No	No	No
workingman	Yes	No	No	No

As nouns, workman and workingman are synonyms defined as:

workman and workingman: an employee who performs manual or industrial labor

Other synonyms of workman include working man, working person.

workman (noun)	workingman (noun)
an employee who performs manual or industrial labor	an employee who performs manual or industrial labor