La mujer es vieja (cuando se trata de personas, es más respetuoso decir "anciana"). La casa es antigua/vieja. El perro es viejo. El carro es viejo/antiguo. ----------------- En general ambas palabras son sinónimos, pero por lo menos en mi país, "antiguo" es más utilizado en cosas sin vida.

Para seres animados es mas utilizado decir viejo / anciano pero por respeto,consideración a las personas es mejor decir "anciano o anciana". Para objetos es más utilizado "antiguo o antigua"

Let´s go see the difference: "antiguo" use to something that have many years, or decades, or centuries, but their conservation is very good. For example, a building with 50 years, but that have good painting, not broken glass, so we say in spanish that the building is "antiguo". Don´t "viejo". "viejo" we use to things that not have a good condition, for example, a bulding with only two years, but have bad conditions, so is "viejo". One car from 2012, but that have bad conditions, "es un coche viejo". Now, to finish, to make mention to older people, we use the word "Grande". For example, "mi papá está grande". My father is older. We can say "Mi papa está viejo", but will not make the other person feel good. In this case, using "viejo" is like say that the father is in bad conditions.