research worker vs researcher

research worker and researcher both are nouns.

Word	Noun	Adjective	Verb	Adverb
research worker	Yes	No	No	No
researcher	Yes	No	No	No

As nouns, research worker and researcher are synonyms defined as:

research worker and researcher: a scientist who devotes himself to doing research

Other synonyms of research worker include investigator.

research worker (noun)	researcher (noun)
a scientist who devotes himself to doing research	a scientist who devotes himself to doing research