The first similarity between the fashion capitals of London and New York is the multi-cultural influence on the design of fashion in these centers. Both cities have diverse ethnic populations. These populations' have a direct impact on what designers in these cities are working on. Designers strive to bring products to market that speak to the sensibilities and needs of this varied group as a whole. Designers will incorporate the best elements of style from different cultures, while adding their own unique twist, to create fashion that speaks to many ethnic groups. Hence, why a certain style or trend becomes immensely popular with people across cultures.
The second similarity between the two fashion capitals is the host of resources available to fashion designers and manufacturers of fashionable goods. London and New York both have a rich history of fashion design. Therefore, there exists the infrastructure in place in each city that enables them to continue to be leaders in fashion. Both cities have academic institutions in place that educate new recruits into the field. Consequently, both cities can draw on an immense talent pool. Major fashion houses, suppliers, designers and modelling agencies exist in each city as well. These cater to the needs of the industry in each city.
One difference between the two fashion capitals is the influence of different surrounding countries on their fashion initiatives. London is influenced heavily by the United Kingdom as a whole, and by Europe in general and Paris, France in particular. New York is influenced by the broad diversity of the 50 U.S States, and to a lesser extent Canada, Mexico, and Latin and South America.
Another difference between the fashion capitals, London and New York, is the significant influence of the monarchy - British Royalty - on fashion. While royal style has a global influence, it is the strongest in Britain, and more specifically London, than anywhere else. Much fashion design in London follows the lead of the Royal Family, especially since the marriage of William and Catherine. It has less of an influence in the United States.