The answer to 'difference between furnace and boiler' is that a furnace and a boiler are two different types of home heating systems. A furnace heats air and distributes it through ductwork, while a boiler heats water and distributes the hot water or steam through pipes. Furnaces are more common in homes with forced-air heating systems, while boilers are often used in homes with hydronic (water-based) heating systems.
Furnaces are generally less expensive to install than boilers, but boilers can be more energy-efficient and provide more even heating throughout a home. Boilers also have the added benefit of providing hot water for domestic use, while furnaces do not. However, boilers can be more complex to maintain and repair than furnaces.