Continental margins are edges of continents or land that are below the ocean’s surface and the large, deep slopes that plunge to the sea floor. There are two types of continental margins: passive margins and active margins.
Passive margins are where continental and oceanic transitions are not on a plate boundary. There is no transitions from one plate to another; there is simply one plate. They tend to be fairly wide and have little seismic or volcanic activity. They form after continents rupture apart, creating a new ocean basin between them.
Active margins are where continental and oceanic transitions are located on a plate boundary. There is a transition from one plate to another; there are two plates involved in this activity. Active margins are relatively narrow and there is a fair amount of active volcanic activity and earthquakes that occur.