Answer:
Narcotics change the flow brains chemicals, because they have sleep-inducing properties due to the decreased neurotransmitters activities. So, basically, narcotics don't improve physical activity.
Stimulants speed up the body functions but depress the brain activity. They are also called psychostimulants, which are used to performance-enhancing, because increase the activity of neurotransmitters.
Marijuana is the Cannabis sativa or Cannabis indica plants. It's a psychoactive drug used for medical and recreational purposes. Also, marijuana changes how the hippocampus processes sensations. Actually, hippocampus abnormalities, like reduced volume, is related to Cannabis abuse, this is way people have this constantly sensation of surreality.