How does the American democracy differ from the democracy that grew under Pericles?

The fundamental distinction between Ancient Athenian democracy and US democracy is that the Ancient Athenians had a direct democracy in which all persons entitled to vote would vote on all issues and the US has an indirect democracy in which all persons entitled to vote will vote for representatives who will then vote on all issues.

However, there are other differences. Ancient Athenian democracy was limited in several ways. The first were limits on suffrage. Only ethnic Athenian males who owned property were allowed to vote. This was less than 10% of the population of Athens. There were also limits on who could be the leaders of the state, restricting that to several noble families. Conversely, in the US, because of amendments to the Constitution any person above the age of eighteen years is entitled to vote and any person who follows the requisite conditions (which are conditions for which any citizen could qualify) can achieve any office in the country (excepting the Presidency which requires a US birth).