Answer:
Both New York and Buenos Aires are huge, cosmopolitan cities which are great business and art centers. First, the main difference about them and what makes each of them unique has to do with the fact that Buenos Aires is the capital city of Argentina, while New York is not a capital city.
Secondly, while Porteños (Buenos Aires citizens) speak Spanish, New Yorkers speak English. However, both cities are full of tourists from all over the world so all languages can be heard walking down their streets.
Third, most of the population in both cities work in big companies and commute regularly, so after-office parties can be seen in the Manhattan as well in Puerto Madero, which is a lovely walk by the docks near Rio de la Plata.
Fourth, citizens usually spend their free time and weekends in the park, such as Central Park in New York and smaller parks in Buenos Aires, like the Japanese Garden and Palermo Forest. Thus, the places are often crowded with joggers, young people and families.
Fifth, as regards food, New Yorkers enjoy hamburguers, hot dogs and Chinese food. Porteños, on the other hand, are fond of barbecue, pizza and empanadas.
Finally, New York is a larger city full of impressive, modern buildings and skyscrapers, while Buenos Aires has a more European appearance. In fact, even though it also has magnificent modern constructions, it is often called the Paris of South America due to its mixture of French and English architecture.