Difference in Normal Stiffness Definition Between EDEM and PFC (Linear Spring Model)

I am currently studying the linear elastic contact models in EDEM and PFC (Particle Flow Code) manuals and noticed a difference in how normal stiffness (kn) is defined between the two softwares. I would like to clarify whether these models would produce consistent results if identical material parameters (e.g., elastic modulus, particle radii, density, etc.) are used. As a newcomer to DEM simulations, I would greatly appreciate your insights to help me understand the rationale behind these distinctions.