longshoreman vs loader

longshoreman and loader both are nouns.

Word	Noun	Adjective	Verb	Adverb
longshoreman	Yes	No	No	No
loader	Yes	No	No	No

As nouns, longshoreman and loader are synonyms defined as:

longshoreman and loader: a laborer who loads and unloads vessels in a port

Other synonyms of longshoreman include dock-walloper, dock worker, docker, dockhand, dockworker, lumper, stevedore.

longshoreman (noun)	loader (noun)
a laborer who loads and unloads vessels in a port	a laborer who loads and unloads vessels in a port
	an attendant who loads guns for someone shooting game