What is a major difference between the united nations and the european union?

What from the columbian exchange had perhaps the biggest impact on the world?

Match each person with his contribution. aristotle socrates eratosthenes hippocrates he studied the causes of illnesses in search of cures. he created a teaching method that involved asking questions. he determined that earth was round. he educated alexander the great.

Did the both the us and ussr have atomic weapons after 1949