Reina vs. dama
While both reina and dama can be translated as queen in English, their usage in Spanish is very different. Reina is the direct and most common word for a queen as a monarch, whereas dama is used for queen only in specific contexts like games.
Reina
A2This is the primary and most direct translation for queen. It refers to a female monarch who rules a country, the wife of a king, or the winner of a competition. It is also the name for the most powerful piece in chess.
La Reina Isabel II de Inglaterra tuvo un reinado muy largo.
(Queen Elizabeth II of England had a very long reign.)
En ajedrez, la reina es la pieza con más poder en el tablero.
(In chess, the queen is the most powerful piece on the board.)
Mi sobrina fue elegida reina del festival de la primavera.
(My niece was chosen queen of the spring festival.)
La abeja reina es fundamental para la supervivencia de la colmena.
(The queen bee is essential for the survival of the hive.)
El cantante se refirió a su madre como 'la reina de su corazón'.
(The singer referred to his mother as the queen of his heart.)
Dama
B1This word's main meaning is lady. It is only translated as queen in the context of playing cards and the games of checkers and chess. Using dama to refer to a female monarch is incorrect.
Para ganar la partida, necesito la dama de corazones.
(To win the game, I need the queen of hearts.)
El juego de las damas es muy popular en mi país.
(The game of checkers (draughts) is very popular in my country.)
Si tu ficha llega al otro lado del tablero, se convierte en dama.
(If your piece reaches the other side of the board, it becomes a queen (kinged).)
La Primera Dama dio un discurso inspirador.
(The First Lady gave an inspiring speech.)
Abrió la puerta del coche para la dama, como un verdadero caballero.
(He opened the car door for the lady, like a true gentleman.)
Summary
In summary, always use reina when referring to a monarch (a country's queen), a beauty queen, or the chess piece. Use dama specifically for the queen in a deck of cards or in the game of checkers (damas). In most other situations, dama simply means lady.