pipe fitter vs journeyman

pipe fitter and journeyman both are nouns.

Word	Noun	Adjective	Verb	Adverb
pipe fitter	Yes	No	No	No
journeyman	Yes	No	No	No

As nouns, journeyman is a hypernym of pipe fitter; that is, journeyman is a word with a broader meaning than pipe fitter:

pipe fitter: a craftsman who installs and repairs pipes and fixtures and appliances
journeyman: a skilled worker who practices some trade or handicraft

Other hypernyms of pipe fitter include artificer, artisan, craftsman.

pipe fitter (noun)	journeyman (noun)
a craftsman who installs and repairs pipes and fixtures and appliances	a skilled worker who practices some trade or handicraft