Aren't Athenians a type of person in ancient Greece, and they lived in Athens, and had often disputes with Sparta?
Yes, but Sparta was a City-State of Greece
I'm not gonna go into to much detail about this but...
Athens was the capital of Greece, and Sparta did not like that. This caused many disputes and I believe there was a war (I can't think of the name at the top of my head) that was caused by this.