How did citizenship in ancient Greece differ from citizenship in modern countries?

The requirements of the citizenship in ancient Greece was that men under the age of 18 would not be a citizen. In 451 B.C the rules of citizenship became stricter. Men could become citizens only if their father and mother's father were citizens. Slaves could not vote or choose their own jobs. Women that were married or unmarried could not own land. Out of 300,000 inhabitants of Tyrants only 45,000 could become citizens