teller vs bank clerk

teller and bank clerk both are nouns.

Word	Noun	Adjective	Verb	Adverb
teller	Yes	No	No	No
bank clerk	Yes	No	No	No

As nouns, teller and bank clerk are synonyms defined as:

teller and bank clerk: an employee of a bank who receives and pays out money

Other synonyms of teller include cashier.

teller (noun)	bank clerk (noun)
an employee of a bank who receives and pays out money	an employee of a bank who receives and pays out money
an official appointed to count the votes (especially in legislative assembly)
someone who tells a story