Just to clarify. Amphetamine Salts ER (Extended Release) is the name listed on generic brands of Adderall XR (eXtended Release). Though the purity and quality of the salts may differ slightly from those used in Adderall, they are the same. And they are...

1/4 dextroamphetamine saccharate
1/4 dextroamphetamine sulfate
1/4 (racemic dextro/levo-)amphetamine aspartate monohydrate
1/4 (racemic dextro/levo-)amphetamine sulfate

(Taken from http://en.wikipedia.org/wiki/Adderall#Chemistry)

("Racemic" is a complicated scientific term that I can't explain, nor do I fully understand. You can read the Wikipedia article here: http://en.wikipedia.org/wiki/Racemic_mixture)