When Charles III became King his wife Camilla, formerly styled Duchess of Cornwall, became known as The Queen Consort.
So, what is the difference between a Queen and a Queen Consort? To put it simply, a Queen Consort is the wife of the reigning monarch, a Queen is the monarch or joint monarch.
A Queen Consort does not have any of the constitutional power of her husband, but she is one of the Counsellors of State and can act for the King, in certain areas, during his absence.
However, a Queen Consort can also be referred to as Queen, plus her name. On 4 April 2023, Buckingham Palace confirmed that The Queen Consort would be known, from that date, as Queen Camilla.
Other Queenly terminology to consider:
Queen Regent - a Queen who rules pro tempore either because the monarch is a minor or because the king is absent or unable to discharge his duties.
Queen Dowager - the style afforded to the widow of a king
Queen Mother - the style afforded to the mother of the reigning monarch who was also the former Queen Consort