“Heavy Pot Use Can Cause Physical Dependence: Heavy marijuana users who stop cold turkey experience a host of withdrawal symptoms, including irritability, anxiety, and depression, but most symptoms begin to lessen after 10 days or so” - http://www.webmd.com/mental-health/addiction/news/20001127/heavy-pot-use-can-cause-physical-dependence
By contrast, alcohol withdrawal can be fatal: “Alcohol withdrawal symptoms can begin as early as two hours after the last drink, persist for weeks, and range from mild anxiety and shakiness to severe complications, such as seizures and delirium tremens (also called DTs). The death rate from DTs — which are characterized by confusion, rapid heartbeat, and fever — is estimated to range from 1% to 5%.” - http://www.webmd.com/mental-health/addiction/alcohol-withdrawal-symptoms-treatments
Yeah.