How is plate tectonics related to continental drift?

In continental drift theory, Wegener had thought of all the continents to have initially existed as a supercontinent in the form of Pangaea. He argued that, around 200 million years ago, the supercontinent, Pangaea, began to split. Pangaea first broke into two large continental masses as Laurasia and Gondwanaland forming the northern and southern components respectively. But according to plate tectonics theory, continental masses, resting on the plates, have been wandering all through the geological period, and Pangaea was a result of the converging of different continental masses that were parts of one or the other plates. Scientists using the palaeomagnetic data have determined the positions held by each of the present continental landmasses in different geological periods

Further Reading:

• NCERT Notes: Continental Drift [Geography Notes For UPSC]
• Geography Notes