rail-splitter vs manual laborer

rail-splitter and manual laborer both are nouns.

Word	Noun	Adjective	Verb	Adverb
rail-splitter	Yes	No	No	No
manual laborer	Yes	No	No	No

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

rail-splitter: a laborer who splits logs to build split-rail fences
manual laborer: someone who works with their hands; someone engaged in manual labor

Other hypernyms of rail-splitter include jack, laborer, labourer.

rail-splitter (noun)	manual laborer (noun)
a laborer who splits logs to build split-rail fences	someone who works with their hands; someone engaged in manual labor