There are 3 types of plate boundaries
CONVERGENT,DIVERGENT,TRANSFORM ( see the pic above for a better perspective)
DIVERGENT : Divergent plate boundaries are separating .When they are separating the lithosphere is pulled apart. it usually breaks going parallel.As the plats split the the block between the faults crack and drops down into the asthenosphere .
CONVERGENT: convergent is an actively deforming area where two or more plates of the lithosphere move twoard one another and collide . A result to the pressure , and plate mleating into the mantle is that it can creat volcanos!
TRANSFORM:transform plate boundaries are places were plats slide past each other. the most famous Transform plate boundary is SAN ANDREAS FULT . Altho transform boundaries are not marked by spectacular surface there motion can cause big EARTHQUAKS !!!!!!!!!!!