Bill Lauto, GTG
The Recessed ceiling fixture shown on the left has two 13 watt Quad energy saving bulbs. Yet, the product is inefficient compared to the design shown in the image just below on the left.
A large percentage of the light output from the top fixture is lost inside the fixture itself. So two bulbs are really needed to do the job of one bulb because of the side mounted design. Those two black spaces toward the right side of the fixture are holes. They allow room for when you pull the bulbs out for replacement. Miss the opening and you risk breaking the bulb and cutting your hand. Also those two holes in every fixture allow warm air to escape up into the ceiling, thus increasing heating costs. The transformers or ballast to start the two bulbs are within the ceiling at the back of the fixture. If a ballast had to be replaced, that job's labor will wipe out the energy savings.
The fixture shown at the bottom has one 15 watt flood with its reflector built in, thus giving the same light level at task, as the two bulbs above. No holes to lose heat and the bulb screws in and out for easy replacement because the ballast is built into the 15 watt flood light bulb.
Some newer fixtures have a higher wattage bulb mounted sideways, but they still have most of the same issues as the top fixture. The only difference is a higher installation cost, because you will be putting in two fixtures compared to just one fixture to have the same light level output as the bottom fixture.
Knowledge truly is Power.