From Wikipedia: Although Portuguese and Spanish are closely related, to the point of having a considerable degree of mutual intelligibility, there are also important differences between them, which can pose difficulties for people acquainted with one of the languages who attempt to learn the other. Both are part of a broader group known as West Iberian Romance, which also includes several other languages or dialects with fewer speakers, all of which are mutually intelligible to some degree.
The most obvious differences are in pronunciation. The written languages are often significantly more intercomprehensible than the spoken languages. Compare, for example, the phrase:
A buen entendedor pocas palabras bastan (Spanish [a ˈβwen entendeˈðor ˈpokas paˈlaβɾas ˈbastan]) and Para bom entendedor, poucas palavras bastam (Brazilian Portuguese [p(a)ɾɐ ˈbõw ĩtẽdeˈdoʁ ˈpoːkɐs pɐˈlavɾɐz ˈbastɐ̃w], European Portuguese [p(ə)ɾə ˈβõ ẽtẽdɨˈðoɾ ˈpo(w)kəʃ pəˈlavɾəʒ ˈβaʃtə̃w]), roughly equivalent to the English proverb "A word to the wise is sufficient."
In the case of names, i don't think that there would be much difference.
