Delivery of Heat
Forced air heat is usually created by a furnace and delivered through a ventilation system. This is the system most commonly used in American homes. Hot water heat is created by a hot water heater, which pushes the water through devices like radiators or baseboard heaters; or in more modern homes radiant floor heating, which consists of a system of tubes installed under floor tiles.
Heat Distribution Through a Room
Forced air heat is popular because it offers the most even coverage in a room. The heat is blown through the air and reaches most areas of the home, while heat provided by baseboards or radiators is more localized. Radiant floor heating keeps the entire room warm, but the heat doesn't extend to the ceiling.
Cost Efficiency
Hot water heating generally uses less energy than forced air heating, making it less expensive. Homeowners are also usually able to set their thermostats lower when using hot water heating, further reducing energy costs.