A hemisphere is half the world. The Western Hemisphere includes North and South America and a part of Africa. The Eastern Hemisphere includes most of Africa, Europe, Asia, and Australia.
A continent is a huge land mass. These are the seven continents: Antarctica, Australia, Africa, Asia, Europe, North America and South America.
A country is a part of a continent (except for Australia). North America includes the countries of Canada, United States, Mexico, Guatemala, Costa Rica, Honduras, Costa Rica, and Panama.