Blue light refers to electromagnetic waves having a wavelength from around 450-495 nanometers.
I think an aesthetic physician will be better able to answer your specific question about how aesthetic blue lights differ from that emitted by electronic screens.
My feeling is they differ in intensity, as well as possibly the exact wavelengths being emitted.
But I think your real question has to do with this conundrum: How is it that blue light is supposed to be bad, such that people are trying to block out blue light from screens, and yet they are using it to treat skin conditions? What is so different about the blue light that is used therapeutically?
You might like to read my earlier answer on LED lights vs fluorescent lights in this regard: https://www.human.com.sg/questions/what-is-the-effect-of-led-light-versus-fluorescent-light-on-eye-health
So in the first place, blue light from screens is not as bad as many people make it out to be. Having said that, there are concerns that excess blue light at night may disrupt sleep patterns.
One of the biggest differences, is that light from electronic screens is meant to be shone into the eyes, for us to see what is being displayed. Blue light used for skin treatments is not meant to be shone into the eyes-in fact people undergoing such treatments usually wear protective eye covers while undergoing such treatments. The intensity of such lights for skin treatments is generally higher than what is used for screens.
Now, is blue light really harmful to the skin? or the eyes?
Consider that drinking too much water can make you very sick. Or eating too much fatty foods can give you heart problems. And yet we definitely need to drink water everyday, as well as have some amount of oil in your diet.
As long as we do not exceed limits as have been determined by research studies, therapeutic blue light devices for skin problems should be safe. As far as electronic screens and the eye go, there is still no clinical evidence that the blue light they emit has any bad effects on the health of the eye.
