There are also two different time frames of tolerance, acute tolerance and chronic tolerance.
Acute tolerance occurs within the course of a single exposure to alcohol.
Chronic tolerance is the gradual decrease in degree of intoxication at the same blood alcohol levels. The maximum degree of tolerance to alcohol is considerably smaller than the tolerance that can develop to benzodiazepines or opiates. The exact mechanism of functional tolerance is not fully understood, but it appears to be related to the development of physical dependence. While alcoholics may have a higher tolerance for alcohol than social drinkers or abstainers, the size of a lethal dose is not much greater than for others.