“The terms “drug abuse” and “drug addiction” are often used interchangeably, but in fact, denote very different conditions. The term “drug abuse” refers to the use of a substance in a manner that deviates from the culturally acceptable norms, while the term “drug addiction” describes a disorder where the drug appears to be the dominant influence on the individual’s behavior.”
“More specially, drug addiction is behavioral syndrome where the individual’s motivation is dominated by the procurement and use of a drug and where the normal constraints on the individual’s behavior are largely ineffective. This condition may or may not be accompanied by physical dependence, but it does seem to be invariably accompanied by psychological dependence. Psychological dependence, however, is NOT equivalent to addiction. Psychological dependence, like its physical dependence counterpart, simply means that the individual requires the substance for normal psychological functioning”
Chemical Dependency Counseling 