The formation of the Andes and Himalayas can be explained by the theory of plate tectonics through the interaction of different types of plate boundaries.

Andes Formation:

• Subduction Zone: The oceanic Nazca Plate subducts beneath the continental South American Plate.
• Convergent Boundary: This oceanic-continental interaction creates a convergent boundary.
• Volcanic Activity: Subduction leads to melting of the oceanic plate, resulting in volcanic activity.
• Uplift and Folding: The overriding continental plate is uplifted and folded, forming the Andes.

Himalayas Formation:

• Continental Collision: The Indian Plate collides with the Eurasian Plate.
• Convergent Boundary: This interaction is between two continental plates.
• No Subduction: Neither plate subducts due to their buoyant continental crusts.
• Crustal Thickening: The collision causes thickening and folding of the crust.
• Uplift: The crustal material is pushed upwards, creating the Himalayas.

Thus, while both mountain ranges arise from convergent plate boundaries, the Andes involve oceanic-continental subduction, and the Himalayas result from continental-continental collision, leading to differences in their geological characteristics and formation processes.