Air handlers and furnaces aren't typically used in the same home in Kansas City. If you use a furnace, you probably won’t need to consider an air handler.
Air handlers are usually used with heat pumps and manage airflow around your house. Some units also offer secondary heating and cooling parts to support the heat pump.
A furnace works differently by blowing heated air into your vents, which circulate it throughout your residence. Because furnaces rely on combustion chambers to produce warmth, they don't need some of the pieces you'll find in a standard air handler.