What drives contintental drift?

You're on the right track here. We believe both convection and subduction are responsible for continental drift. It used to be taught that convection currents rising up from the Earth's mantle and moving along the bottom of Earth's crust was the primary driver of continental drift. This has since been updated, where scientists believe subduction is a much stronger driver. A subduction zone is where heavier, denser oceanic crust is pulled beneath continental crust due to gravity. This typically happens at coastlines where oceanic crust meets continental crust. The way to picture it is almost like a curtain opening in the middle where the edges of the window are the subduction zones and the oceanic ridges are where the curtain separates.