It's really very simple. Both of these programs are based on tests for energy efficiency. Products carrying their logos have displayed high efficiency. But the two programs have different histories, cover different products and are under different management.
The U.S. Environmental Protection Agency launched the Energy Star program in 1992 in an effort to reduce air pollution. The idea behind Energy Star is simple. If more people use more energy-efficient lights and appliances, they will use less electricity. That means power plants won't have to burn as much coal, oil and other energy sources to produce electricity, resulting in fewer emissions and less air pollution. Along with helping to save the environment, the Energy Star program also helps consumers save money by showing them energy-efficient products. To get the Energy Star label of approval, manufacturers must submit their products, which include appliances as well as lighting products, for third-party testing. After a product has been approved, it’s still subject to random testing when it’s on the market, to make sure that manufacturers are adhering to the energy limits they originally attained.
Although participation is voluntary for manufacturers, thousands of products have received an Energy Star rating, and billions have been sold. The program has spread beyond the U.S. to other countries.
DLC, short for Design Lights Consortium, has a similar aim - to save energy, the environment and money - but it's aimed just at commercial operations and just at lighting products. Founded by the Northeast Energy Efficiency Partnerships in 1998, the program originally began in the Northeast and Mid-Atlantic states, but it has spread across much of the U.S. and Canada. In the DLC program, lights also are subject to strict, third-party testing, which manufacturers must pay for.