1. In principle, there is no difference between the two, they are both aimed at heat transfer of cold and hot fluids. 2. But you can't mix the two. (1) the concept of heat exchanger something is broader, including all the heat exchanger something for the purpose of heat exchange. For example, radiation heat exchanger, convection heat exchanger, plate heat exchanger, needle heat exchanger, heat pipe heat exchanger, spoiler heat exchanger, regenerative heat exchanger, gas heat exchanger, gas-liquid heat exchanger, etc. These are the so-called heat exchangers. (2) of course, evaporator and condenser also belong to a type of heat exchanger, but this type of heat exchanger has phase change, more special. Therefore, the name is usually based on the working fluid phase change to show the difference with the ordinary heat exchanger. For example, gas condensation, called the condenser something, of course, the liquid evaporation, called the evaporator. However, they still belong to the category of heat exchanger. (3) other special applications include convection (shield, high temperature, low temperature) superheaters, high temperature (low temperature) reheaters, economizers, and so on, which are named after their purpose or use. In fact, these are also more special use or special field applications of a class of heat exchangers.