Marijuana vs Alcohol
To intoxicate, marijuana and alcohol disrupt proper brain function - but they do it differently. Proper brain function requires a variety of neurotransmitters that the body produces when it needs them. Cannabinoids are one type of neurotransmitter, of which correct amounts are always required for optimal brain health.
THC - the substance in marijuana that makes a user “high” is actually a cannabinoid. It is also a hallucinogen, that specifically activates the endocannabinoid receptor system in the brain and disrupts normal cannabinoid-based function (movement, memory and a variety of emotional functions) in the process of creating the high. Distorted feedback and failed memory storage caused by the THC, spoofs the brain. Flooding the brain with THC also has the potential to rewire it to require greater amounts of cannabinoid neurotransmitters that the brain cannot produce. In contrast, alcohol is a depressant that physically alters cellular membranes if consumed in intoxicating quantities - this changes the way cells and neurotransmitters function together creating drunkenness. Consequently, alcohol can disrupts overall brain function for a time versus THC that alters a specific-set of functions and potentially rewires it. Below are other comparisons between the two substances.
Marijuana effects are persistent - More on fat vs. water solubility
A note on psychosis and violence - “Violence that drinking causes is largely predicable. Alcohol intoxicates. It dis-inhibits users. It escalates conflict. It turns arguments into fights, fights into assaults, and assaults into murders. Marijuana is an intoxicant that can dis-inhibit users, too. And though it sends many people into a relaxed haze, it also frequently causes paranoia and psychosis… paranoia and psychosis cause violence… [When those in psychotic states, experience terror that] becomes too much, some people with psychosis snap. But when they break, they don't escalate in predictable ways. They take hammers to their families. They decide their friends are devils and shoot them. They push strangers in front of trains.” – Alex Berenson, Tell Your Children: the truth about marijuana, mental illness and violence