clerk vs shop boy

clerk and shop boy both are nouns.

Word	Noun	Adjective	Verb	Adverb
clerk	Yes	No	Yes	No
shop boy	Yes	No	No	No

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

Other hyponyms of clerk include shop girl.

clerk (noun)	shop boy (noun)
an employee who performs clerical work (e.g., keeps records or accounts)	a young male shop assistant
a salesperson in a store

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