Athens and Sparta

The Spartans had two kings, which each ruled a separate thing in the city. For example, the first king might run agriculture, whereas the second takes care of other everyday things.
Sparta also had a 'council of elders', consisting of 28 men who were aged 60+.
This meant Sparta was an oligarchy.

The Athenians, on the other hand, were democratic...sort of.
The men who owned land were the only people who were allowed to vote. Women, children, slaves, and men without any land could watch - but not take part in the proceedings.

Athens and Sparta also had many other differences. For example, Sparta was Ares's best bud. They loved war. Athens, though, valued reason. Sure, war was inevitable sometimes, but if they could avoid it, all the better!
Because Sparta liked war, they had to have a very strong army. Boys were thrown into the forest when they were 7. if they survived the next 5 years, they made their way back to Sparta to begin training for the army. They stayed in the army from age 18-30. Women, if they chose, could also go into the army, but they couldn't go into the forest. Spartan women could also own property. Athenian women couldn't.
Athenian men were only in the army for 2 years. They were not thrown into the forest, and they were not treated like dirt. They were educated in literacy, mathematics, music and health.
The two city-states had lots more differences, including currency - Spartans used iron rods, instead of coins, which is what Athenians used - Food - Athenians were traders, Spartans grew their own food - and architecture - Athenians were very grand compared to Spartans.