The answer to 'difference between air handler and' is that an air handler and a furnace are two distinct components of a central HVAC system. An air handler is the indoor unit that circulates air throughout your home, while a furnace is the component that generates heated air.
The key differences are that an air handler does not generate heat on its own - it simply moves the air, while a furnace is responsible for heating the air. Air handlers can be used with other heat sources like heat pumps or boilers, while furnaces have their own heat source, usually a gas burner or electric heating element. Air handlers are generally more energy-efficient and quieter than furnaces, but furnaces provide more powerful heating capacity.