A habit is a pattern of behavior that is continuous and is within a person's control. An addiction is a dependence on a certain behavior or behaviors that a person MUST do and has lost their free will. An addiction leads people to other behaviors to "feed" their addictions that they would not normally do including stealing, lying, hurting loved ones, going into debt, and can lead to depression/suicide.
Addictions can be deadly due to consequences of the addiction such as drug use and alcohol. It has been long thought that all addictions are the same. It is true most addictions affect the same part of the brain but new research has shown that different parts of the brain are "excited" such as gambling.
A study was conducted on patients diagnosed with compulsive gambling and MRI tests show that a different part of the mid-section of the brain is excited vs other addictions. The consequences of addictions also differ such as addiction to sex can result in unplanned pregnancy, emotional damage, Sexually Transmitted Diseases (STD's) including HIV.
Cannabis or marijuana is addictive contrary to popular belief. While it may become legal there are two different diagnoses given to patients whom use marijuana including "cannabis abuse" and "cannabis addiction". These are psychiatric/medical diagnoses and this addiction has been often found to lead to other drugs.
The most proven treatment methods for any addiction which is pathological or "causing significant impairment in a person's life including social, professional, interpersonal relationships" is the 12-step program, group counseling, individual counseling and if the addiction is drug or alcohol abuse residential treatment is vital for safe recovery.
People attempting to stop using certain drugs and alcohol oftentimes are at high risk of hallucinations, stroke, coma, and/or death. Counseling and support are also very important for recovery and continued sobriety. The brain usually changes after 28 days not "using" or "engaging" in the addictive behavior and the addict has a significant increased chance of staying free from the bondage of addiction. Follow-up treatment is an essential part of staying free from the addiction including going to meetings including AA, GA, NA, Celebrate Recovery, and several other free group/support meetings usually held in churches or hospitals.
There are often state funded programs which pay most or all the treatment for people whom are addicted to drugs or alcohol. Gamblers Anonymous and Narcotics Anonymous meetings are free and accountability is an important part of treatment.
If you have further questions talk to a qualified mental health professional and/or your primary care doctor. Most people who have treated addictions have been an addict themselves and understand the lifelong journey it takes for you to get help and what it will take to OVERCOME. While addictions are destructive and deadly there is always hope but you have to decide if you are ready to change or nothing and nobody can do anything for you.