A sign is something others, like the doctor, see, whilst a symptom is something that the patient discerns and explains. To give an example, enlarged pupils can be a sign, whilst sleepiness can be a symptom.
Substance dependence is when someone is addicted to a something like drugs or alcohol and they are not able to control their use of the substance. Though these may be dangerous to them, they go ahead with alcohol consumption (the possible dangers may or may not be clear to the person)
Drug addiction can lead to strong cravings. The person addicted may be willing to stop taking it, but they are not able on their own.
Personal circumstances, genetics, and the specific substance being used are all things that can determine how the signs and symptoms of abuse will manifest in an individual.
Signs and symptoms of substance enslavement may include:
Certain alcohol or substance abusers who aren't technically addicted might also be affected by or cause a few of the above-mentioned descriptions, though these abusers don't generally experience the withdrawal symptoms of addicts or the exact same obsession to use the substance.