I also believe tobacco is worse, but any sort of smoke carries the risk of lung cancer. Incense in a poorly-ventilated room or eating smoked fish can do it. In short=all smoke is bad, but some types more than others.

Tobacco is worse than marijuana. More addictive, more carcinogenic, and more likely to damage the respiratory system. I don't consider myself pro-marijuana (I'd never use it myself), but I do think it should be legalized.