Air handlers and furnaces aren't usually found side by side in Miami. If you rely on a furnace, you most likely won’t need to think about an air handler.
Air handlers are often linked with heat pumps and manage airflow throughout your house. Some systems also offer extra heating and cooling components to assist the heat pump.
A furnace runs in a different way by blowing warm air into your vents, which circulate it across your residence. Because furnaces rely on combustion chambers to create hot air, they don't need some of the components you'll spot in a normal air handler.