What is the difference between amphetamine/dextroamphetamine salts and only dextroamphetamine salts?

Active drug. Amphetamine has mirror-image versions (d- and l-). D-amphetamine (dexedrine) is the active version. Adderall (dextroamphetamine and racemic amphetamine) is a mix of d- and l-amphetamine that has been popular for treating adhd since mid 80's. The argument--not proven--is that the l-amphetamine "smooths" out the effects, so people are less apt to be irritable while taking it for their adhd.