To put it another way, the British Empire had a "merchantalist" foundation - maintain a positive balance of trade and surplus material assets by forcing its colonies to engage in trade on preferential terms - while the U.S. has been "free trade" oriented in its imperial years, with balance of trade being less important than retaining GDP.
Both have imperial dynamics, but for the U.S. the important part is being the "world's policeman" as it comes with the authority to destabilize regions and install puppets where their sovereign governments may act against U.S. interests. With this more limited administrative footprint, they're free to focus on use of violence and propaganda, while taking up domestic market policies that benefit net importer businesses and thus justify maintaining the empire.
Where people say that the Pax Americana is ending it is in part because the dynamic has grown more multipolar since the end of the Cold War, with a diverse group of nations asserting their interests without being overthrown.
Both have imperial dynamics, but for the U.S. the important part is being the "world's policeman" as it comes with the authority to destabilize regions and install puppets where their sovereign governments may act against U.S. interests. With this more limited administrative footprint, they're free to focus on use of violence and propaganda, while taking up domestic market policies that benefit net importer businesses and thus justify maintaining the empire.
Where people say that the Pax Americana is ending it is in part because the dynamic has grown more multipolar since the end of the Cold War, with a diverse group of nations asserting their interests without being overthrown.