Pump up the Heat!

I have heard home construction professionals talk a lot about heat pumps, but I didn't know if a heat pump and a furnace were the same or if they were different. I really felt like a dummy, so I consulted Chapter Five of the Virginia Energy Savers Handbook, and it gave me all this great information:
"Heat pumps work on a completely different principle than electric furnaces. Instead of just converting electricity into heat, a heat pump uses an electric compressor that "pumps" heat from one place to another.
"Heat flows naturally from hot to cold, never from cold to hot. Water flows naturally from a high level to a low level, never uphill. Just as a water pump moves water from a low level to a high level- against the direction of its natural flow- a heat pump moves heat from a cold area to a warm area.
"Refrigerators, air conditioners, and heat pumps are all basically the same. In a refrigerator, heat is pumped from the cold freezer and refrigerator compartments out into the warmer room. In an air conditioner, heat is pumped from the cool interior of the house into the hot outdoors. In a heat pump, heat is pumped from the cold outdoors to the warm interior of the house.
"In fact, heat pump/air conditioner combinations use the same equipment for both jobs, using a flow control valve to change the direction of heat pumping from summer to winter. This ability to use the same basic equipment for heating and air conditioning is a prime advantage of heat pumps.
"A heat pump makes much better use of electricity than an electric resistance furnace. For each Btu of energy that comes into the heat pump from the electric power line, it can pump one or two more Btu's from the outdoors. In this way it
delivers two or three times more heat than an electric furnace for the same electric input.
"All heat pumps have the same basic components: a compressor which does the actual "pumping", an indoor coil which heats or cools circulating house air, an outdoor heat source which supplies heat or cooling to the system, and copper tubing that circulates high pressure refrigerant fluid between the indoor and outdoor units.
"Residential heat pumps can utilize heat sources down to 20-30oF to heat indoor air up to 80-100oF. Heat pumps can also be used for water heating.

The Virginia Energy Savers Handbook 2008: Department of Mechanical Engineering of Virginia Tech Blacksburg, VA 24060