Europe is a continent
US is a country
Slovenia is a country
Slovenia plays USA tomorrow
THis is a misconception. Technically the United States are a series of "states". Slovenia is a state, probably a "nation-state".
IN its original inception, the U.S. government was to be a loose federalization of independent states. The U.S. is simply a stronger version of the European Union.
In reality, a state in the United STates is somewhere between a province and a separate "state" but please don't let terminology fool you.
Just to be more clear, the term "state" is not necessarily coterminous or coextensive with "nation" or "country". State typically refers to the political organization of a geographic area. Country can refer to a geographic region. A "Nation" most commonly refers to the people within a geographic region( even though it does not necessarily have to be within a certain region).