I'm not so sure. They are both bad. They are also not comparable.
Sure they are, in the fact that they are both psychoactive substances, like coffee or nicotine. Where they're not comparable is 1) current legal status and 2) to my knowledge, nobody has asserted that ethanol has beneficial effects on the body. I know that there are studies showing red wine seems to lower the risk of fatal heart disease, but IIRC it's the antioxidants in the wine that do the good, not the alcohol.
And you'll also have to define "bad" for me. That could mean anything, it's totally subjective.
People tend to do stupid things with their body, and laws are here to reduce the various means to harm oneself.
You're not going to get anywhere with this argument if you're talking to the typical American. Once they hear something like 'protecting people from themselves' they immediately shut down and insist that anything the government does is bad if it forces them to modify their behavior (even if they would do so voluntarily, were there no law. They'll engage in the regulated behavior that they ordinarily would not do just to be spiteful). The theory is that you've got an inalienable right to be a total idiot. Where that falls down for me is the fact that frequently your choice to be a total idiot affects me negatively; for example, let's take motorcycle helmet laws. If you ride a motorcycle without a helmet the chances of you being severely injured or dying in an accident are increased. Sure, it's your body, go on with your bad self, but when you get hurt you incur medical costs. If you have private insurance (like most Americans) this increases their costs, so in order to protect their profit margins, they hike my premium. Same goes for life insurance; if you threaten their profits, they'll just charge everybody more. And the crazy thing is that most bikers would wear helmets voluntarily, so the requirement doesn't affect them at all. They see it as just one more freedom taken away if it's codified into law, and that is the worst thing that could ever happen, even if they would do it anyway.
It's science, not politics !
Sorry, this is just plain wrong. In the case of marijuana, its prohibition in the USA was not intended to protect public health, but to negatively impact the Mexican population that was crossing the border. That isn't science, it's racism. In addition, the science is starting to disagree with you. There isn't a whole lot of data at this point (at least in the USA, due to pot's Schedule I status) but hopefully (and this goes back to the subject of TFA) this will change as attitudes towards marijuana change (a majority of the population now believes it should be legalized).