We certainly do.
We know that half to 2/3 of long term smokers will die as a direct result, losing on average a decade of life. It causes 15 types of cancer, it's a leading cause of cardiovascular disease including heart disease and stroke, it causes COPD and increases the risk of diabetes, asthma, MS, rheumatoid arthritis, mental health issues, dementia, early menopause, impotence, miscarriage, still birth, low birth weight and chronic, serious gum disease. We know that smoking damages just about every organ in the body.
That's before even starting on the harms it does to those around the smoker, including three times the risk of SIDS and serious respiratory illness in children.
We don't know everything about vaping but we really do know quite a lot now - enough to be confident that the potential risks of vaping are not remotely in the same ball park.
I don't know what you're trying to achieve with your child but it's unlikely to be successful:
The Chief Medical Officer, Professor Sir Chris Whitty, has put the case very succinctly, “The key points about vaping (e-cigarettes) can be easily summarised. If you smoke, vaping is much safer; if you don’t smoke, don’t vape.”
Yet fewer than one in ten smokers understand this, and media coverage often fails to make this clear. In 2023, more than a quarter of adult smokers have never tried vaping to help them quit smoking, although it is one of the most effective quitting aids
And although representation of vaping in a way which overstates the risk can discourage adult smokers from vaping, it isn’t an effective deterrent for adolescents, who are more likely to engage in risky behaviour than adults, and are more susceptible to peer pressure. Indeed in 2023 despite more than half all adolescents believing vaping to be more than or equally as harmful as smoking, the highest proportion ever recorded, we also have the highest proportion trying vaping.
https://ash.org.uk/resources/view/addressing-common-myths-about-vaping-putting-the-evidence-in-context