Air coolers and evaporative air coolers are both types of cooling systems that use air to reduce the temperature of a space. The main difference between the two is that air coolers use a refrigerant to cool the air, while evaporative air coolers use the process of evaporation to cool the air. Air coolers are more efficient and require less energy to operate, but they are also more expensive and require more maintenance. Evaporative air coolers are less expensive and require less maintenance, but they are less efficient and require more energy to operate. Additionally, evaporative air coolers are better suited for dry climates, while air coolers are better suited for humid climates.