Alcohol
Impaired mental functioning
Liver disorders
Gastrointestinal problems
Heart disease and stroke
Lung disorders
Cancer
Skin, muscle, and bone disorders
Pregnancy and infant development complications
Increased risk for other addictions
Pregnant Women who consume alcohol during pregnancy may give birth to infants with fetal alcohol syndrome. Infants with fetal alcohol syndrome may be afflicted with physical and mental abnormalities.
Does alcohol have any health benefits?
Drinking wine in moderation can be good for your heart, but it's also bad for your liver. Alcohol has never been known to cure or help with any diseases, only cause cirrosis of the liver, heart disease and failure, and kidney damage/failure. You could say that it's helpful in cleaning cuts and scrapes, but you don't drink that kind of alcohol. Ingestion does not help, only hurt.
Marijuana
First off, marijuana does prove to be helpful with a few ailments, particularly: treating glaucoma, multiple sclerosis, epilepsy, and appetite loss in cancer and AIDS patients. Research also suggests cannabinoids kill cancerous cells in cases of leukemia, lymphoma, breast and prostate cancer, and more.
Marijuana may hurt your short term memory and make you forgetful, or apathetic about things, but in case you didn't know, humans have cannabinoid receptors in the brain to bind with cannabinoids, and naturally existing cannabinoids in the body which closely resemble the chemical makeup of THC. These cannabinoids help erradicate painful memories and misfortune.
And, well, getting lung cancer from smoking pot? Well, shit...if you smoke anything it's bound to be bad for your lungs.
Sources:
alcohol -
http://www.alcoholismtreatment.info/effects-of-alcoholism.html
marijuana -
http://www.straightdope.com/columns/060414.html
So, when I look at it, you'd be better off smoking a bowl every day than drinking a six-pack every day.