Laser light is coherent another words the laser light photons travel in one direction. LED light is not coherent and the LED photons travel in all directions but will still have good effects. My experience is that laser light will travel much deeper into the muscle tissue than LED. For example, when I have neck pain I can take my 635nm laser and shine it in the front of my neck and within a few minutes the muscles in the back of my neck begin to loosen. With my LED light this barely happens. There is this mindset in the laser therapy community that you need lots of laser power to get good results ie 500-1000mw or more. I have found the opposite to be true. The body responds very well to small amounts of power in the order of 5-10mw. This is called bio-stimulation or stimulating the body to heal itself. With high power laser you are heating up the tissue which does have some postive therapeutic effects but is not truly biostimulative. Plus with lower power there are virtually no safety issues, just don't shine directly into the eyes.