Doubt with para and a

[Amigoo]

Hello. I've problems with these sentences:
Una carta para España. - The letter to Spain.
El tren a Madrid. - The train to Madrid.
My MX friend says that sound silly in Mexico. I'm confused, maybe that's correct in Spain Spanish, cos I'm learning castellano Spanish?

[Tomisimo]

I'm not exactly sure what your question is. In many cases, "a" and "para" can be used somewhat interchangeably.

Voy a la casa.
Voy para la casa.

[AngelicaDeAlquezar]

I agree with Tomísimo. In this case, "a" and "para" both imply a destination.