Is there a difference between focalin (dexmethylphenidate) xr and adderall xr?

A big difference!: Focalin (dexmethylphenidate) is the active half or methylphenidate (ritalin). Adderall is a mix of amphetamine salts and of amphetamine isomers. Both can be highly beneficial for treating adhd, but they are different chemicals altogether and may work through slightly different mechanisms. If one doesn't work or has too many side effects, the other may prove better--and it doesn't matter which you try first.