caster vs worker

caster and worker both are nouns.

Word	Noun	Adjective	Verb	Adverb
caster	Yes	No	No	No
worker	Yes	No	No	No

As nouns, worker is a hypernym of caster; that is, worker is a word with a broader meaning than caster:

caster (noun)	worker (noun)
a pivoting roller attached to the bottom of furniture or trucks or portable machines to make them movable	sterile member of a colony of social insects that forages for food and cares for the larvae
a shaker with a perforated top for sprinkling powdered sugar	a person who works at a specific occupation
a worker who casts molten metal into finished products	a member of the working class (not necessarily employed)
	a person who acts and gets things done