Final answer:
The east and west sides of South America have different tectonic characteristics; the west is defined by the subduction of the Nazca Plate under the South American Plate, forming the Andes, while the east does not have major tectonic activity but slowly moves away from the Mid-Atlantic Ridge.
Step-by-step explanation:
The east and west sides of South America differ significantly in terms of plate tectonics. The west coast of South America is characterized by the subduction of the Nazca Plate beneath the South American Plate, which has led to the formation of the Andes Mountains - a prominent feature in the landscape. This subduction zone is a convergent plate boundary, where the oceanic crust of the Nazca Plate is forced under the continental crust of the South American Plate, creating a zone of high seismic and volcanic activity.
On the other hand, the east side of South America does not have such dramatic tectonic boundaries. There are no major plate boundaries comparable to the west coast's, as the South American Plate on this side moves away from the Mid-Atlantic Ridge, which is actually located in the Atlantic Ocean. Consequently, the eastern part of the continent does not have the same level of seismic activity or mountainous terrain as the west. However, the South American Plate does interact with other plates, like the African Plate, but these boundaries are much further east, beyond the continent's borders, resulting in the divergent boundary at the Mid-Atlantic Ridge, where new oceanic crust is generated.