What is different in American democracy than in Greek democracy?

I believe this question is referring to the democratic government of Athens, which from around 500 to 300 B.C. was a powerful city-state. Athenian democracy was far more direct than American democratic government. For example, laws and other important acts of government were carried out in a mass meeting of citizens held about once every two weeks. These decisions were made by majority vote. Citizens were also chosen by lot--not elected--to serve on the Athenian court and city council. This meant all citizens had an obligation, not just a right, to serve in government. American democracy, on the other hand, is generally representative democracy. Through elections, the people choose their representatives in local, state, and national government, and the people they choose, theoretically at least, represent their interests. The size of the United States, and the variance of regional interests, has led to a relatively decentralized system known as federalism, a far cry from the direct democracy possible in a city-state like Athens. On the other hand, modern American democracy is far more open to popular participation than in Athens. Only a relatively small proportion of men were considered citizens, and only citizens could vote or participate in government. In the United States, very few restrictions on citizenship exist, and political participation is open to all citizens.