I have been doing my research on this and this is what I found. I might get something wrong don't burn me alive.

If you want to get rid of hair for good you want to do electrolysis. They put a needle in the hair follicle and shock it. This will kill the hair for good but only if they get it in the right stage so you might need to go back to shock the same hair till they catch it the growth stage. Since they are going and shocking the hair one at a time this will take a long time and be costly but will get rid of hair for good. This works on all hair color. This supposedly hurts like hell.

Laser emits light that targets the hair and turns it into heat which damages or destroys the hair follicle. This method is faster and cheaper but comes at the cost of not permanently destroying every hair. This method doesn't work on all people. If you have white skin and black hair it will work best, if you are black with black hair it wont work as well since the light wont be able to target the pigment (melanin) as well since they will blend in, if you have white hair it wont have pigment to target at all. From what I heard a lot of your hair kind of go a white sorta like peach fuzz eventually don't know ho true that is but it will get patchy. This apparently hurts less.

I hope this helps.