Young Brunette Girl On The Wharf By The Sea

In everyday parlance the term quay is common in the United Kingdom and many other Commonwealth countries, whereas the term wharf is more common in North America. In commercial/industrial usage wharf is typically avoided with quay being used to refer to the berthing areas, and port and terminal being used to refer to the overall structures and locations. Merriam-Webster's Dictionary of Synonyms quotes the New York Times as saying "a quay is a docking facility at which vessels lie parallel to the shoreline." In some contexts wharf and quay may be used to mean pier, berth, or jetty, though these uses are not addressed.
In old ports such as London (which once had around 1700 wharves ) many old wharves have been converted to residential or office use.