What is the difference between coated vs. uncoated Calcium Carbonate (CaCO3)?

Well, the coated Calcium Carbonate has particles which easily disperse in the resin and other components that constitute an adhesive composition, and impart excellent viscosity stability and highly improved adhesion to the resulting adhesive.

I got this information from a Google search and this site:
Surface-coated calcium carbonate particles, method for manufacturing same, and adhesive - Patent 6686044