Air handlers and furnaces aren't usually installed side by side in Grand Island. If you use a furnace, you most likely won’t need to spend time thinking about an air handler.
Air handlers are usually used with heat pumps and manage airflow around your house. Some units also have secondary heating and cooling pieces to help the heat pump.
A furnace heats in a different way by pushing heated air into your vents, which circulate it around your residence. As furnaces use combustion chambers to create heat, they don't have some of the pieces you'll find in a regular air handler.