How Can Lasers Kill Hair AND Grow Hair?

Doc…what’s your lay person’s take on laser therapy?? Seems odd you can use a laser to remove hair and also try grow it…sorry to bug you, just emailed you not too long ago…anyhow, they’re advertising lasercomb on tv, thought I’d ask what you thought of it…

To be honest, I am having difficulty believing that the comb works. A few passes with a comb through your hair each day brings hair back? My brain tells me not to believe it. The lasers that kill hair are different so look at them as a totally different product with a commonality in name.