Muy fácil. Key: - Clave: Representa un código y/o palabra secreta. - Llave: Se usa para abrir puertas, candados, etc. Saludos.

In spanish Key means: Llave or clave

Llave: it's for a padlock or when you open a door . Clave : it's like a password or code

I guess you refer to a sheet containing the right answers to the test and not the blank template where you should write your answers. 'Clave' is usually employed as a synonym to 'contraseña' that translates as 'password'. It's not usual to refer to an answer sheet as 'las claves' o 'hoja de claves' but it would be understood. 'Hoja de respuestas' refers exactly to the blank template where the student writes down his answers to the test and not to the printed one with the solutions. This one is usually called 'planilla de respuestas' o just 'planilla' (specially if it is a punched page with holes for the right answers). 'Clave' can also mean 'key' in the meaning of something central and determinant for a given concept. But never as a physical thing that can open a lock. The only way to refer to that concept is 'llave'. Is interesting than both 'clave' and 'llave' come from the same latin word 'clavis'.

Hi, I hope I could help you with an example. Key as llave it´s the tool with you open a door. Key as clave it's a keyword, like when you go to a speakeasy and someone ask you the password, also as clave means something essential i.e. Aquella canción fue la clave para enamorarla. That song was the key to make her fall in love with me.