Islamically speaking, what's the difference between Adderall and Marijuana?

Well, I am nothing close to a scholar but I will try to give this answer a shot. The reason may be not so much the drug itself, but the culture that surrounds it. Marijuana has a distinct culture that follows it wherever it can be found, whereas adderall and pain killers are used solely for medicinal purposes (at least that is what they are giving out for). A person who takes these drugs does so that they be able to better there health or become more active members in their communities (either through more energy or because they can focus better) Almost anything that we ingest can result in negative consequences to our bodies if it is taken in an incorrect or excessive manner. Even water can you if drink too much. So if marijuana becomes more widely accepted as a medical drug instead of a recreational one, more scholars might be willing to state that its use is okay, or at the very least remove the haram status.