longshoreman vs manual laborer

longshoreman and manual laborer both are nouns.

Word	Noun	Adjective	Verb	Adverb
longshoreman	Yes	No	No	No
manual laborer	Yes	No	No	No

As nouns, manual laborer is a hypernym of longshoreman; that is, manual laborer is a word with a broader meaning than longshoreman:

longshoreman: a laborer who loads and unloads vessels in a port
manual laborer: someone who works with their hands; someone engaged in manual labor

Other hypernyms of longshoreman include jack, laborer, labourer.

longshoreman (noun)	manual laborer (noun)
a laborer who loads and unloads vessels in a port	someone who works with their hands; someone engaged in manual labor