How do tectonic plates move and what is the difference between oceanic and continental crust?

Tectonic plates make up the crust of the earth, that sit on top of the mantle. The mantle is a layer of liquid rock. Convection currents in the mantle move the plates across their surface. Oceanic plates are more dense than continental plates, and often when these two different types of plates meet, they form a subduction zone. Here, the oceanic plate is forced underneath the continental plate, and the oceanic plate is melted by the heat of the mantle.