What is the difference between direct and indirect expansion type evaporator?

In the direct expansion evaporator, it is the cooling fluid itself of the refrigeration system that carries out the final cooling process, ie the withdrawal of heat from the medium to be cooled. Thus, for example, in a window air conditioner, the ambient air, which is the medium to be cooled, comes into contact with the coil of the evaporator, inside which evaporates the cooling fluid from the cooling system. In the indirect expansion evaporator, there is a fluid intermediate the refrigerant in the refrigeration system, and the medium to be cooled. That is, the refrigerant in the refrigeration system will cool an intermediate fluid, and this fluid will remove heat from the medium to be cooled. So, for example, in a large chiller / fan-coil type air conditioning system, the chiller refrigerant gas (chiller) performs the water cooling, producing ice water. This cold water will cool the air in air-conditioned environments, in fan-coil