Air handlers and furnaces aren't typically installed side by side in Jackson. If you use a furnace, you probably won’t need to consider an air handler.
Air handlers are often linked with heat pumps and control airflow across your house. Some models also have secondary heating and cooling pieces to assist the heat pump.
A furnace works in a different manner by sending heated air into your vents, which send it throughout your home. As furnaces rely on combustion chambers to make heat, they don't use some of the pieces you'll find in a normal air handler.