Prezygotic isolation is a type of reproductive isolation that occurs before the formation of a zygote can take place. In most cases mating does not even occur. Forms of prezygotic isolation include spatial, behavioral, mechanical and temporal isolation.
Postzygotic isolation on the other hand occurs after members of two different species have mated and produced a zygote. Forms of postzygotic isolation includes; hybrid sterility, hybrid inviability and hybrid breakdown.
Therefore; Prezygotic isolation prevents the fertilization of eggs while postzygotic isolation prevents the formation of fertile offspring.
