Here's a breakdown:

* Continental Drift: Proposed by Alfred Wegener in the early 20th century, this theory suggested that the continents were once joined together in a supercontinent called Pangaea and had drifted apart over millions of years. It was initially met with skepticism because Wegener couldn't explain the mechanism driving the continents' movement.

* Plate Tectonics: This theory, which developed in the 1960s, builds upon continental drift by explaining the mechanism of movement. It states that Earth's outer layer (the lithosphere) is broken into large, rigid plates that move and interact with each other. This movement is driven by convection currents in the mantle, a layer beneath the lithosphere.

Plate tectonics provided a comprehensive explanation for:

* The distribution of continents and oceans: It explains how continents moved apart and how new oceanic crust is created at mid-ocean ridges.

* The formation of mountain ranges: Plate collisions create mountain ranges like the Himalayas.

* The occurrence of earthquakes and volcanoes: These phenomena are concentrated along plate boundaries where plates interact.

Essentially, plate tectonics took the ideas of continental drift and expanded upon them, providing a more complete and scientifically supported explanation for the dynamic nature of Earth's surface.