workman vs labourer

workman and labourer both are nouns.

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

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

workman: an employee who performs manual or industrial labor
labourer: someone who works with their hands; someone engaged in manual labor

workman (noun)	labourer (noun)
an employee who performs manual or industrial labor	someone who works with their hands; someone engaged in manual labor