How did the modern Olympic games differ from the ancient Greek ones?

Everyone knows that the Olympic Games originated in ancient Greece. But if you look at modern games, then they are significantly different from those that were before. The most important difference is the number of participating countries and sports. Today there are several times more of them than before. There is also one more important difference, this is that today both men and women take part, and before only men. In addition, the games were previously held in Olympia, and today they are held all over the world at intervals of four years.