Laser hair removal - destroyed vs damaged follicle?

Do laser/ipl destroy or damage the hair follicle? Why would some follicles be destroyed and other damaged? What causes this? The settings of the laser? My understanding is hair follicles that are destroyed Means the hair from that follicles will never grow back while a damaged follicle will delay hair growing from a few months to a year? Once a follicle is damaged can it be destroyed? If yes, would you need more laser sessions for a damaged hair follicle vs a non damaged follicle to destroy it?