"It is true that the functionality of both the residential and the commercial HVAC units are the same but still there are a few prominent differences between the two units.First of all a commercial HVAC unit is bigger in size than a residential HVAC unit. This is because commercial HVAC units have to cool a larger space when compared to a residential unit. And that is the reason commercial HVAC units are more complex in nature than the residential units.Commercial HVAC units are located mostly on rooftops while the residential units are located on the backyard or on the side of the buildings.Like all other aspects commercial and residential HVAC units have difference in their drainage system as well. In case of residential unit it drains into a single pan while in case of commercial unit multiple pans and pipes are required for the purpose of draining.The commercial units are packaged which means both heating and cooling is embedded in a single unit while the residential units are split. They have an indoor unit and an outdoor unit. The indoor unit has the evaporator and the outdoor unit has the compressor.The commercial HVAC units are modular in structure and the residential units are standalone structures. The result is commercial HVAC units are more flexible than the residential HVAC units."