Both amphetamine and methamphetamine have the same chemical base, and the process they undergo can drastically alter the effect on the body. Doctors prescribe amphetamines. They can increase focus and heighten mental clarity, and for this reason, they are widely prescribed to relieve the symptoms of those who have attention deficit disorder and attention deficit hyperactivity disorder.
Amphetamines are methylated once. Methamphetamine is double methylated. Methamphetamine is very dangerous for this reason, and doctors do not prescribe it. It is highly addictive and illegal. It is also significantly faster acting and far more potent than amphetamine.
Both of these drugs work on increasing norepinephrine and dopamine in the brain. Methamphetamine is never safe. However, amphetamines can be taken with safety if it is under the supervision of a prescribing doctor.