Unlike Mesoamerican civilizations, Mississippian "Mound Builder" societies had no social class differences.

False--they did have social class division.

The Mississippian Mound Builders had different social classes in their society. There were priests and shamans connected to the religion and temples. For the remaining people they were divided between the Suns (chiefs), Nobles, Honored Men and Honored Women, and the lower class.