Central heating simply means a central heating unit, such as a furnace, heats the entire house, as opposed to individual room heating units (think the old days with fireplaces in several different rooms and no other means of heating).

I think you are talking about the difference between a heat pump and a furnace. You call the heat pump your "Central Heat& Air Unit".

Anyways, it sounds like you already understand about the heat pump. It consists of both an outdoor unit and indoor coil which can provide heat in the winter and a/c in the winter by moving heat from outside to inside or vice versa using electricity.

A gas furnace is only one piece and it sits INSIDE the house. It generates its own heat by burning natural gas and then blows house air over the heat exchanger to get you warm air inside your house. It's source of heat is the gas and oinly requires electricity to run its blower and electronics.

Hope that's what you needed...

Heat pumps sit outside. They inside unit is properly known as the air handler.

Some heat pumps are in package systems. They combine the air handler and heat pump into one unit, which sits outside. Sometimes the are mounted on the roof. Ducts are run into the house. There are also package AC units with no heating capability, or with heat strips only.

Gas furnaces (propane or NG) can also be combined with an air handler and AC condenser into a package unit which sits outside. They are commonly known as gas packs.

"Gas furnaces (propane or NG) can also be combined with an air handler and AC condenser into a package unit which sits outside. They are commonly known as gas packs."

That makes the most sense. My heat from my Central heat and Air unit is fueled by gas and is entirely outside, so there is not an inside furnace of any kind - a "packaged system". I guess that up North, having the furnace outside would be too counter-productive, and would likely need to be bigger than what I would need in the South as well.

I guess my question actually was "is the external gas heating unit for my house actually a furnace, or something different?"

The furnaces from family up North are these huge monstrosities in their basements, so I thought what's in my small external heating unit outside might be something different. Guess not.

Here is a link that might be useful: How a packaged system works