The joke probably makes more sense in Japan because if you don't know much about the states North Carolina, USA and South Carolina, USA seem practically the same.
Americans probably know how to separate them based on cities, sports teams, politics, and universities.
The two girls are drawn way too similar. It was hard telling them apart in that fight. One of them should have had black hair or short hair or something.
@Kurapica
Thanks for picking this up!
If you stick with it I hope you translate the computer code spells. The last group didn't bother but those are fun to read.