Split AC systems differ from window units in that they are composed of two separate components: an outdoor condenser and an indoor air handler. The condenser is responsible for releasing heat from the refrigerant, while the air handler is responsible for circulating the cooled air throughout the space. Split AC systems are more efficient than window units because they are able to cool larger spaces more evenly and with less energy. Additionally, split AC systems are quieter and more aesthetically pleasing than window units, as the outdoor condenser can be placed away from the living space.