Cráneo vs. calavera
In the Spanish language, both 'cráneo' and 'calavera' refer to parts of the skeletal structure of the head. While they are sometimes used interchangeably, there are subtle differences in their usage and connotation.
Cráneo
The term 'cráneo' refers specifically to the bony structure that encloses and protects the brain. It is a scientific and anatomical term used in formal contexts.
El neurocirujano estudió detenidamente el cráneo del paciente antes de la operación.
(The neurosurgeon studied the patient's cranium carefully before the operation.)
En la clase de anatomía, aprendimos las diferentes partes que componen el cráneo humano.
(In anatomy class, we learned the different parts that make up the human skull.)
Calavera
'Calavera' can also mean the skull, but often includes the jawbone and is more associated with symbolic and cultural references, such as artwork or Dia de los Muertos (Day of the Dead) celebrations.
Durante el Día de los Muertos, se ven muchas calaveras decoradas en los altares.
(During Day of the Dead, many decorated skulls can be seen on altars.)
El pirata tenía un tatuaje de una calavera con dos huesos cruzados en su brazo.
(The pirate had a tattoo of a skull with two crossed bones on his arm.)
Summary
To summarize, 'cráneo' is used in a more scientific and anatomical context, referring to the bone structure that protects the brain, whereas 'calavera' can refer to the entire skull, including cultural or artistic representations. Despite their similar meanings, their use differs depending on the context.