clerk vs mapper

clerk and mapper both are nouns.

Word	Noun	Adjective	Verb	Adverb
clerk	Yes	No	Yes	No
mapper	Yes	No	No	No

As nouns, mapper is a hyponym of clerk; that is, mapper is a word with a more specific, narrower meaning than clerk:

clerk: an employee who performs clerical work (e.g., keeps records or accounts)
mapper: a clerk who marks data on a chart

clerk (noun)	mapper (noun)
an employee who performs clerical work (e.g., keeps records or accounts)	a clerk who marks data on a chart
a salesperson in a store

clerk (verb)	mapper (verb)
work as a clerk, as in the legal business