Air handlers and furnaces aren't usually found together in Pierre. If you use a furnace, you most likely won’t need to spend time thinking about an air handler.
Air handlers are frequently used with heat pumps and deliver airflow across your house. Some units also provide secondary heating and cooling parts to assist the heat pump.
A furnace works in a different way by blowing warm air into your vents, which send it around your home. Since furnaces have combustion chambers to make heat, they don't need some of the parts you'll see in a normal air handler.