How is the structure of the Roman republic different from the democracy in Athens?

The difference is that in Athens, a popular assembly ruled, and in ancient Rome, power was concentrated in the hands of the republican senate. Although both there, and there, officials were elected by voting. Also, state issues were resolved. In Rome itself, the republic was abolished during the reign of Octavian Augustus. This happened when he took the imperial throne in 27 BC. It also marked the transformation of Rome into an empire.