This is a terrible comparison. Meth[amphetamine] and Adderall [amphetamine] are extremely similar. Both act as triple monoamine releasers, releasing the most norepinephrine followed by dopamine followed by serotonin.

The methyl group attached to the amine basically just helps it cross the blood brain barrier better and makes it more resistant to enzymatic destruction. This means it is a couple times more potent dose-per-dose and lasts longer. It's nothing like the difference between methanol and ethanol, where one will kill you and the other is fine to drink. That IMO a rationalization people with ADHD make to convince themselves their prescribed amphetamines are somehow qualitatively different than big scary meth--just like the rationalization that amphetamine acts magically different in people with ADHD (it calms everyone down in low doses, it just might not provide the same working-memory deficit correcting effects as there is no deficit). In fact, in most of Europe, amphetamine itself is what you find on the streets, not meth.

Bingo