https://www.serviceexperts.com/faq/what-is-the-difference-between-an-air-handler-and-furnace

Air handlers and furnaces aren't typically installed in the same home in North America. If you have a furnace, you most likely won’t need to think about an air handler. Air handlers are frequently paired with heat pumps and manage airflow across your residence. Some systems also provide extra heating and cooling pieces to support the heat pump. A furnace heats in a different manner by pushing heated air into your vents, which send it across your residence. Since furnaces depend on combustion chambers to produce heated air, they don't have some of the parts you'll see in a standard air handler.

What is the Difference Between an Air Handler and Furnace?

Air handlers and furnaces aren't often installed in the same home in Austin. If you use a furnace, you most likely don't need to spend time thinking about an air handler.

Air handlers are typically linked with heat pumps and deliver airflow across your residence. Some models also offer extra heating and cooling components to support the heat pump.

A furnace works differently by blowing warm air into your vents, which circulate it around your home. As furnaces have combustion chambers to produce hot air, they don't use some of the components you'll spot in a regular air handler.