What's the difference between Cohesive Zone Model and Joints Element in discrete element method?

Hi,

I am a PhD student working on rock mechanics. I have studied Cohesive Method for a few times. But I am confused on What the special functions the Cohesive element have compared with Discrete method? 

For one DEM software UDEC， model is consisted of solid elements and joints elements. What's the difference between Cohesive element and Goodman element?