The names of these two things in the industry are quite confusing, because the two things are indeed very similar.
As far as you mentioned, the heater core refers to the radiator core in the "warm air tank" mentioned in your question, and the evaporator core refers to the radiator (cooling) in the cold air box. heater core. The function of the core is to heat or cool the air flowing through it. The structures are very similar. Most of them are structures with pipes and radiators penetrated, and the box assemblies are equipped with centrifugal fans. The difference is that the hot water (antifreeze) from the engine flows in the heater pipe, and the refrigerant in the air conditioning system flows in the evaporator.