1(800) 615-1067Substance use refers to the act of using a substance, such as alcohol or drugs, in any amount or frequency. Substance abuse, on the other hand, is defined as the use of a substance in a way that causes significant impairment or distress and may lead to negative consequences, such as health problems, legal issues, or problems with relationships or work. Substance abuse is a more severe form of substance use that requires professional intervention and treatment.