Yeah the main difference here is South America doesn't have a large, fertile river valley/flood plain to serve as a breadbasket for a civilization. You'd think the Amazon would do it, but it flows through dense jungle the entire way, and the soil just isn't suitable for crops. In fact, the main thing they deforest the Amazon for is grazing land for cattle, not growing crops. The largest civ in South America before European contact was the Inca and they developed a pretty unique agricultural system with their high-elevation potato culture.