How is Sparta and Athens similar in social structure?

Sparta and Athens both had hierarchical social structures that included distinct classes, such as free citizens, non-citizens, and slaves. In both city-states, citizenship was highly valued and often limited to a specific group based on birth or status. Additionally, both societies relied on a large population of enslaved individuals to support their economies and daily functions. Despite their differing focuses—militaristic in Sparta and democratic in Athens—both shared fundamental social stratifications.