clerk vs desk clerk

clerk and desk clerk both are nouns.

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

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

clerk: an employee who performs clerical work (e.g., keeps records or accounts)
desk clerk: a hotel receptionist

clerk (noun)	desk clerk (noun)
an employee who performs clerical work (e.g., keeps records or accounts)	a hotel receptionist
a salesperson in a store

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