Air handlers and furnaces aren't usually installed side by side in Hurricane. If you use a furnace, you probably won’t need to consider an air handler.
Air handlers are typically paired with heat pumps and manage airflow around your residence. Some systems also have backup heating and cooling parts to assist the heat pump.
A furnace works in a different way by blowing warm air into your vents, which circulate it around your house. As furnaces rely on combustion chambers to make heat, they don't use some of the parts you'll find in a standard air handler.