Tricky question. I don't know anything about the treatment of slaves in the American South. However, I can tell you that there are a few fundamental differences between 19th-century chattel slavery and the helot system used by the ancient Spartans.

The main thing is that helots were not the personal property of the Spartiates whose lands they worked on. They could not be bought or sold. They were owned by the Spartan community as a whole, in the sense that they had to do what the Spartans told them to do, but they were not a commercial item. They were not brought in from abroad like slaves, but worked the land of their home country, like the subjugated populations of many other parts of the Greek world.

It is not known how exactly helot labour was used. It seems most likely that they simply tilled small family farms, and owed their produce to the land's Spartiate owner. This was probably quite a hands-off process. Many Spartiates were absentee landlords, since the obligations of citizenship forced them to stay in the town of Sparta much of the time; estates as far afield as Messenia would probably not have gotten much personal attention from their owners.

As a result, helots in those parts maintained their own identity and traditions as Messenians, and when the area was liberated after two and a half centuries of occupation, the foundation of the city of Messene instantly created a stable local rival to Sparta.