I had no idea about the difference - interesting. I thought nicotine itself was a carcinogen though?
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!