Air handlers and furnaces aren't typically found side by side in Indianapolis. If you rely on a furnace, you most likely won’t need to think about an air handler.
Air handlers are often paired with heat pumps and control airflow around your house. Some models also offer backup heating and cooling components to assist the heat pump.
A furnace runs in a different way by blowing warm air into your vents, which send it around your home. Since furnaces depend on combustion chambers to create hot air, they don't have some of the pieces you'll spot in a normal air handler.