Are the edges of plate boundaries the same as the edges of the continents?

The edges of plate boundaries and the edges of continents are generally not the same. When we talk about continents and oceanic crust, we usually refer to the density of the rocks. Continents tend to have less dense rocks, while the oceanic crust consists of denser rocks. Hence, where they meet, the heavier oceanic crust tries to subduct below the lighter continental crust. However, continents are kind of stuck to the more dense oceanic crust and so go along for the ride. A helpful visualization that helps distinguish between the two is provided by the image above.