LED televisions are more energy efficient than LCD televisions because the backlighting source in an LED demands less electricity. However, CNET claims that the difference probably doesn't translate to savings because the initial investment in an LED model is higher, and the energy savings can't recover the expense.
The Energy Star website has energy-use statistics available by brand, display size and type, with values showing that display size has the biggest impact on electrical usage. LED and LCD models are both LCD televisions, or liquid crystal displays, but they differ in backlighting sources. The LED uses light-emitting diodes, while the LCD uses cold-cathode fluorescent lights. Both model's energy efficiency can be increased by turning down the brightness of the backlighting source.