Swedish Snus is cold-cured, while other dip is heat-cured. It is well established that partial combustion of organic matter creates a bunch of different carcinogens. With cigarettes, you are inhaling partial combustion products from plant matter that has already undergone partial combustion once, and you have astronomical cancer risk. With dip, you are putting partially combusted plant matter in your mouth and have quite high cancer risks. With swedish snus, you are putting zero partial combustion, and no discernible cancer risk.
I think the evidence regarding swedish snus shows that it is far less carcinogenic than traditionally-cured oral tobacco, but still significantly carcinogenic. In particular, swedish snus has very little in the way of nitrosamines [1], a major carcinogenic element of heat-cured tobacco products.
RE: harmfulness of nicotine, my impression was that it was a little more harmful to the heart than caffeine. I suppose this would depend on dosage, which is difficult to compare.
I recommend reading it, it's very informative!
In Sweden it used to say "causes cancer" on the tin like it does on cigarettes. But the government removed the warning and now it just carries a nonspecific "harmful to health" warning. I guess that means that there wasn't enough proof that it actually causes cancer. But of course, future research might prove again that it does.
But of course, although snus is a credible safer alternative to cigarettes, it is banned in every other EU country while cigarettes remain completely legal.