CFL stands for compact fluorescent lamp. These are available in several different sizes, from the normal household energy-saving bulbs to the much bigger enviro-lights/eco-lights.
The normal household energy saving bulbs will plug into a standard light bulb holder, however an enviro-light/eco-light needs a bigger type of bulb holder, called a E40 or GES (Giant Edison Screw) holder. Obviously, if you are growing with normal sized bulbs, you will need a lot more of them to provide the same amount of light as a much larger enviro-light/eco-light. Which brings us nicely onto HID lights.
HID (High Intensity Discharge) lights are generally much more powerful than fluorescent lights. However they also produce more heat and require better ventilation. They can be divided into MH (Metal Halide) and HPS (High Pressure Sodium) lamps. MH lights produce more blue light and are better for vegetative growth, whereas HPS lights produce more red light and are better for flowering.
Generally, CFL lights are used for smaller grows, where heat could cause a problem, whereas HID lights are better for larger grows, as they are more powerful and can cover a larger area.
Check out
https://www.rollitup.org/newbie-central/937-how-grow-marijuana.html and
http://www.littlegreenhouse.com/guide3.shtml for more info.
Hope I haven't confused you further
