They are quite different molecularly, Concerta is extended release methylphenidate (instant release is Ritalin) while Adderall is instant release dextroamphetamine and amphetamine. But there's also extended release Adderall too. All in all, it'll come down to your specific neurobiology regarding the best treatment option. However, if appetite suppression is a concern for you, using an instant release med will decrease the amount of time the med is active, which should reduce the duration of any appetite suppression.