2nd/3rd generation light

Ive been ringing various salons and if anyone has heard of Ellipse, well it is said that it uses a “2nd Generation” IPL light. This means that it has some kind of ‘dual control’ where the light is targeted to be absorbed by the melanin in the hair and so there will be less chance of the skin absorbing the light, which could otherwise induce a risk of damage to the tissues.

I recently asked a salon to send me information about Biolaser and on the leaflet it said it uses a 3rd generation light … It said some words to the effect that it uses RED light this time, and that this 3rd generation light is the most technologically advanced thing

What does this mean; why does the hair-removal industry use words “1st/2nd/3rd generation light” ?

If anyone knows could they please respond!