When do I use rostro or cara?
It appears to me that "rostro" and "cara" mean the same thing-"face". Are there times or contexts that would better determine when to use one or the other, or are they equally interchangeable?
As inuyaki said, rostro addresses more abstract concepts such as emotions.
su rostro triste Her sad countenance.
"rostro" is a more intimate word used to describe or talk about someone's face whereas "cara" is more like the actual anatomical structure that is the face.
"rostro" involves abstract concepts and "cara" physical aspects .