odd fellow vs worker

odd fellow and worker both are nouns.

Word	Noun	Adjective	Verb	Adverb
odd fellow	Yes	No	No	No
worker	Yes	No	No	No

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

odd fellow: someone regarded as eccentric or crazy and standing out from a group
worker: a person who acts and gets things done

Other hypernyms of odd fellow include actor, doer.

odd fellow (noun)	worker (noun)
someone regarded as eccentric or crazy and standing out from a group	sterile member of a colony of social insects that forages for food and cares for the larvae
	a person who works at a specific occupation
	a member of the working class (not necessarily employed)
	a person who acts and gets things done