Whats the difference between dosage? Focalin (dexmethylphenidate) 15 mg compared to Adderall 15. What's the differences between the effects?

Focalin (dexmethylphenidate) a bit more. Focalin (dexmethylphenidate) is about the same potency of d-amphetamine. Adderall has both d-amphetamine and l-amphetamine, so 15 mg is not quite is about 75% as potent as 15 mg of amphetamine. That said, individual responses to stimulants vary so much that for any given person, Focalin (dexmethylphenidate) might work much better than Adderall or the other way round. Dose needs are highly individual and requires trying different doses.