It's not complicated when one is aware that context is everything, and that there are no isolated universal translations.
The
RAE gives both expressions as synonymous, but as far as I've seen, the usage of two interactions is usually made by a "
santo y seña" with a
reply, which would be the "
contraseña". This is why we use as translation of "password" too, I guess.
- ¿Quién anda ahí?
- Soy el cabo López. Quiero entrar.
-
La casa azul.
-
El perro verde.
- Puedes pasar.
Here are the dictionary's meanings of "
contraseña". That may make things clearer.
