fireball vs worker

fireball and worker both are nouns.

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

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

Other hypernyms of fireball include actor, doer.

fireball (noun)	worker (noun)
the luminous center of a nuclear explosion	sterile member of a colony of social insects that forages for food and cares for the larvae
a ball of fire (such as the sun or a ball-shaped discharge of lightning)	a person who works at a specific occupation
a highly energetic and indefatigable person	a member of the working class (not necessarily employed)
an especially luminous meteor (sometimes exploding)	a person who acts and gets things done