In 1900, the two biggest cities in the America's were Nueva York, and Buenos Aires.
A european immigrant would flip a coin to decide which to go to.
So, initially, the two cities had a LOT in common.
Of course, they developed in very different ways, but each is a melting pot city, not overly influenced by a colonial overlord, that has absorbed generations of immigrants and created a new, unique mix.
As we have discussed here endlessly, BA is NOT authentically Italian, even though a majority of its citizens are of Italian descent. Its not very spanish. Its not hardly "indio" at all. It is not carib at all, with virtually no African influence. It is different from virtually every city in South or North America.
Love it or hate it, its its own thing.
I have been to Naples, and find very little resemblance, either visually or culturally.
At the very least, there are no Jews to speak of in Naples, and the cultural landscape in BA is heavily influenced by eastern european and german Jewish culture and tradition.
there are some Jews in Naples...
Baron Rothschild sent his sons each to one European financial capital. Paris, Frankfurt and indeed Naples was one too.