There are some significant differences between a drunk and an alcoholic. Over and above, a drunk person is not necessarily an alcoholic. An alcoholic needs to drink an excessive amount of alcohol all the time. It may cause irreparable harm to a person's health, relationships, finances, and career. Alcoholics are people who possess a physical desire to drink alcohol beyond the reasonable limit, regardless of society's rules.
That being said, both drunks and alcoholics are capable of causing a car accident due to their alcohol consumption. Quite often, being drunk is made light of in our society. Going out and getting drunk is like a right of passage to those who are in college. It's a fine line, even in that situation, between alcoholic and drunk.