LED torches use Light Emitting Diodes in place of conventional bulbs. Usually clusters of several diosdes are used together and some can be switched off to increase battery life with less bright light.

LEDs are practically indestructable compared to conventional bulbs .

Power consumption for same brightness of light is less than halogen lamps and so batteries last longer but the brightness varies as the batteries  discharge.
 
 

HID bulbs have no filament. The HID bulb creates light by creating an arc between poles. The result is an extremely bright and powerful beam. Because of the low wattage required a 10-watt HID bulb is approximately equal in light output to a 50-watt quartz halogen bulb, burn times are correspondingly longer with similar batteries.

The HID bulb output has a color temperature essentially the same as the Sun. 

HID bulb life is  related to the number of times you turn the bulb on and off. Once activated, you should give the bulb at least three minutes to warm up to its proper operating temperature before turning it off. You should also wait at least a minute before restarting a bulb that has just been turned off.