Air handlers and furnaces aren't typically installed together in Calgary. If you use a furnace, you likely won’t need to consider an air handler.
Air handlers are often used with heat pumps and manage airflow throughout your home. Some models also offer secondary heating and cooling components to support the heat pump.
A furnace works differently by blowing warm air into your vents, which send it around your home. Since furnaces depend on combustion chambers to make heat, they don't use some of the components you'll find in a standard air handler.