Let me explain you, let me take one country(India) to explain you .
Suppose 10 girls have taken part in Miss India contest so whoso is the winner will be going for Miss World , First Runner up will go for Miss Universe and Second Runner up will go for Miss Earth.
Its only tiltle and entity is different beside that
Miss Universe is American-owned whereas Miss World is British-owned. Miss Universe has never been held in the United Kingdom (where Miss World was born), whereas Miss World has been held in Atlanta, Georgia in 1991.
Hope this clarify