The Atlantic spread's name comes from the body of water that separates the United States and Europe. However, the terms "American option" and "European option" don't really have anything to do with the countries they are named after. An American option is simply one that can be exercised at any time, while a European option is one that can only be exercised at maturity. The latter is usually considered less valuable, since it is less flexible. An option could be more valuable if exercised early, depending on what happens in the market, and American options provide for that possibility.
Investment dictionary. Academic. 2012.