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 the population.
This statement highlights a fundamental difference in the societal structures and membership of the governing bodies in both political systems, illustrating the elitist nature of the Roman Senate compared to the more democratic and participatory system of Athens.