I don't think its as simple as saying that anyone who has negative effects from substance use and continues using it is dependant. Is a coffee drinker a dependant because his teeth turned yellow? Same goes for a smoker.
It has a lot more to do with your ability to lead a normal life, whatever that may mean to you. If you lose your job, your home, or your family, and those things were important to you, but you continue to use the drug that caused it, then you're dependant.
However, if you can still show up to work on time, still take care of your family, pay your bills, then your just a drug user, not a drug dependant.