Answer:
Rome used two systems, depending on the time period, they used the Republic, where people would represent different people, however, later on, they used the Imperial System.
Greece, you can't say it all as one. Athens used absolute democracy, where everyone was equal, as long as you were not a woman, child, or slave. Sparta used oligarchy, which is kind of like a mixture between a republic and a monarchy, in which a small group of people rule over the land. But most of the rest of Greece had monarchies, especially Crete.