Air handlers and furnaces aren't often found together in Columbus. If you use a furnace, you most likely shouldn’t need to think about an air handler.
Air handlers are often linked with heat pumps and control airflow across your home. Some models also offer extra heating and cooling pieces to help the heat pump.
A furnace works in a different manner by sending warm air into your vents, which circulate it across your residence. Because furnaces have combustion chambers to make hot air, they don't use some of the components you'll find in a standard air handler.