working man vs labourer

working man and labourer both are nouns.

Word	Noun	Adjective	Verb	Adverb
working man	Yes	No	No	No
labourer	Yes	No	No	No

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

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

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