What is the difference between Adderall (dextroamphetamine and racemic amphetamine) and Adderall (dextroamphetamine and racemic amphetamine) xr?

Adderall (dextroamphetamine and racemic amphetamine) forms. Immediate release versus extended release.
Length of action. Adderall (dextroamphetamine and racemic amphetamine) is immediate release (ir), lasting about 3-4 hours. Adderall (dextroamphetamine and racemic amphetamine) XR is a blend of beaded capsules, half released immediately and the other half releasedd 3-4 hours later, so one pill should cover 8-10 hours.