Simply the substance used.

Substance abuse and substance dependence are two different things. Substance abuse- is when someone is using a substance more than directed or they are using it for different reasons than what it is for. Substance dependence- is when you have developed a need physicall and/or mentally for it and without it your body in some way experiences a withdrawl.

Substance abuse and dependence refer to any continued pathological use of a medication, non-medically indicated drug (called drugs of abuse), or toxin.

Substance abuse and addiction is called dependence. When a person is addicted to drugs or alcohol, they develop a physical and/or psychological dependence.

Substance abuse and dependence cut across all lines of race, culture, education, and socioeconomic status, leaving no group untouched by their devastating effects.