Secondary succession occurs where there are already a small set a species present, and thus biological life already been able to take a good hold on the area. On the other hand, primary succession occurs in an area devoid of life, and spores from fungi, bacterium or grasses can eventually generate a livable soil for larger plants, and later animals, to take foothold. An example of primary succession would be magma from a volcano sweeping over a large portion of a forest and suffocating all life.
