galley slave vs labourer

galley slave and labourer both are nouns.

Word	Noun	Adjective	Verb	Adverb
galley slave	Yes	No	No	No
labourer	Yes	No	No	No

As nouns, labourer is a hypernym of galley slave; that is, labourer is a word with a broader meaning than galley slave:

galley slave: a laborer who is obliged to do menial work
labourer: someone who works with their hands; someone engaged in manual labor

Other hypernyms of galley slave include jack, laborer, manual laborer.

galley slave (noun)	labourer (noun)
a slave condemned to row in a galley	someone who works with their hands; someone engaged in manual labor
a laborer who is obliged to do menial work