The key difference between methamphetamine and adderall is that meth is neurotoxic at clinical doses, while adderall is actually neuroprotective. Meth use also causes negative side effects like dry mouth, dizziness, etc much more frequently and powerfully than amphetamine. Users also report that meth tends to hit much "harder" compared to amphetamine, increasing its addiction potential. It mostly is the high doses that cause the side effects, but because of the impurities in street meth, it's nearly impossible to properly weigh the amounts required for adderall-like usage(5-10mg), and even then, it's still neurotoxic. This means that most street users use large doses that cause those effects.