The main difference is that Snus is pasteurized, whereas most all American snuff is fire or air cured and fermented.
Swedish snus has much much lower levels of cancer causing Nitrosamines, and they don't increase over time, like American snuff does.
Several studies do show though that American snuff is not nearly as dangerous as has been claimed. It's just that Swedish snus is even lower.
One excption is Timerberwolf smokeless snuff, also from Swedish Match. It has the lowest level of Nitrosamines of any American snuff.
I was just curious if anyone here used snus.