My Little Activity Book

What do you call a person who serves customers and sells items in a retail store?

"We've got openings for ten sales assistants in our new store."

A retail clerk, a salesclerk, shop clerk, retail associate or (BrE) shop assistant or customer service assistant, are the terms used for a service occupation in a retail business.

"Shop assistant is understandable in AmE, but it's not a term that is widely used, at least in the eastern part of the US." 

In BrE, 'shop assistant' or 'sales assistant' are the most common terms. Salesman/woman/person is more often used outside the context of retail sales.

"We wouldn't say 'clerk'. It is normally a word for a person who works in some sort of administrative capacity."

In certain shops you might find a person trained to sell, consult, advise, etc. and not just to take your money at the till. They will probably be on commission. In this case, you might call them a "salesperson", rather than a "shop assistant".

"There are also more specific terms like 'checkout girl' or 'shelf-stacker', as well as the general 'shop/retail worker."

Sales assistant duties usually include selling, restocking and merchandising.

"I complained to the sales assistant, who told me I would have to talk to her manager."

Sales clerk [klɜːrk] is a common NAm term. In the US and Canada, 'salesperson', the general, non-gender-specific term, is also widely used. 

"We also use sales clerk and sales lady." 

A salesperson/man/woman might take a more active role in marketing than a sales clerk. A sales clerk might be no more than a cash register operator, ringing up the prices of items and collecting payment. 

"A sales clerk runs a cash register, provides customer service, and helps keep the store clean."

A salesperson might seek out customers inside the store and touts the advantages of various items. Once the customer has been convinced to buy an item, the salesman turns the customer over to a sales clerk for completion of the transaction.

"An example of a salesclerk is the cashier at a grocery store."

Salesman is also used for people who market products outside the store, either over the telephone or through personal visits.These people wouldn't be called sales clerks or sales assistants. 

"A sales associate is often a title for the person behind the register."

Some retail stores call all of their subordinate staff 'associates' regardless of their function, but that's more of an inflated title than a description of their duties. They might be salesmen, sales clerks, or floor sweepers.

"Sales assistant is in most cases probably just a fancy term for sales clerk." 

Some stores also have stock clerks, who put additional merchandise on the shelves to replace what has been sold, but do not conduct transactions with purchasers.