LED flashlights are considerably more efficient than traditional flashlights (if by 'traditional' you mean one that uses an incandescent bulb).
For one thing, incandescent lamps are more efficient at higher wattages:
en.wikipedia.org/wiki/Incandescent_light_bulb#Power
By the chart on that page, a 5-watt incandescent bulb will generate 5 lumens per watt, compared to a 300-watt bulb that will generate over 20 lumens per watt.
Now contrast that with an LED emitter that may approach "efficacies" (luminous efficiencies) of 100 lumens per watt. A typical ratio between LEDs and incandescent is 10X. This can result in longer runtimes and/or more light output for the same amount of batteries that power the flashlights being compared.
I have numerous LED flashlights, the best I have found are made by Fenix. They make some that fit in the palm of your hand, run on a single AA battery, and are too bright to look directly into.
Regarding specs, here is one of the Fenix LED flashlights I'm talking about:
www.fenix-store.com/product_info.php