Substance abuse and addiction are related but distinct concepts. Substance abuse refers to the pattern of harmful use of substances, such as alcohol or drugs, that leads to negative consequences, such as health problems, social difficulties, or legal issues. Addiction, on the other hand, is a chronic disease characterized by compulsive drug-seeking and drug-taking despite negative consequences.

The transition from substance abuse to addiction can occur gradually, over a period of time, and depends on various factors such as the substance being used, the frequency and quantity of use, genetic and environmental factors, and individual vulnerability. In general, addiction is considered to be a more severe form of substance abuse, where the person experiences physical and psychological dependence on the substance and may have difficulty quitting or reducing their use, even when they want to.