Vyvanse is a prodrug of dextroamphetamine, which means that it turns into that in the body. The advantage allegedly is that it's less prone to abuse but the real reason it exists is that dextroamphetamine entered the market in 1937 and so its patent has long since run out. Dextroamphetamine in turn is just amphetamine with the left-handed isomer removed. This left-handed isomer is less potent than the right, but both promote higher concentrations in the brain of the same chemicals norepinephrine and dopamine.

Amphetamine you may know better under its colloquial name -- speed. That's right, Shire Pharmaceticals is upset that European doctors and parents aren't rushing to give children fancy, expensive, speed.