The main difference between heat exchangers and cooling towers lies in their functions and applications. Cooling towers are designed to reject waste heat to the atmosphere by cooling water through evaporation, while heat exchangers transfer heat between solid objects and fluids or between multiple fluids. Heat exchangers are commonly used in various industries, including space heating, refrigeration, and power generation. Understanding the specific types and specifications of each device can help in selecting the right one for a given application. Both play crucial roles in thermal management systems.