The statement that best explains the differences between the democracy of the Athenian polis and the structure of the Roman Republic is:
The senate of the Roman Republic was composed of wealthy patrician magistrates whereas the Athenian ecclesia and Council of 500 were made up of various citizens drawn by lot from different territories within Athens.
This statement highlights the contrasting composition and democratic principles of the two systems. In Athens, a larger segment of the citizen population participated in government, whereas in Rome, the senate was primarily composed of the wealthy elite.