The answer to 'difference between furnace and heat pump' is that a furnace uses combustion (burning fuel) to generate heat, while a heat pump uses electricity to move heat from one place to another. Furnaces are typically more powerful and better suited for very cold climates, but heat pumps are generally more energy-efficient and can provide both heating and cooling.
Furnaces are powered by natural gas, propane, or electricity and heat the air directly. Heat pumps use refrigerant to absorb heat from the outside air (or ground) and transfer it inside. This makes heat pumps more efficient, as they don't generate heat but simply move it. However, furnaces tend to have a higher heating capacity and work better in very cold temperatures where heat pumps may struggle.