It depends on how they are consumed as well, vaporizers are better than smoking.

Even if they were consumed in the same amount, and even without being filtered, i would still expect tobacco to be more damaging simply do to the toxic cornucopia of additives found in cigarettes.

Oddly enough, the National Cancer Institute has recognized the cancer-fighting properties of cannabis. I'm sure they have also recognized the cancer-causing effects of tobacco.

Not to mention the fact that tobacco restricts your cardiovascular system and cannabis does the opposite. And that tobacco can cause serious health risks to pregnant mothers and there is no evidence to support any adverse effects of cannbis on a fetus. Also, tobacco is one of the top causes of death in America while cannabis has never caused a single recorded death EVER.

I can cite my sources if anyone is interested. :)

You would be correct if it were not for the carcinogens and other as yet unknown chemicals cigarettes add. Tobacco by itself probably isn't any worse than smoking any other plant. Probably tastes like shit though.

but can cause Asthma

Hey, just thought I should point out that my doctor recommended I use marijuana with a vaporiser to possibly cure my asthma in the long run! I have noticed significant benefits from it already. :)