Adderall and Ritalin belong to the same class of medications (called psychostimulants of the central nervous system) for treatment of ADHD (attention deficit hyperactivity disorder). Both are more or less at par as far as their efficacy and popularity are concerned. But there are important differences between Adderall and Ritalin.
Firstly, Adderall and Ritalin are chemically different: Adderall is a mix of four amphetamine salts, while Ritalin is simply methylphenidate, which belongs to the piperidine class of compounds. The difference between Adderall and Ritalin is not just limited to their chemical composition. Their paths of action also differ to some extent.
Both Adderall and Ritalin are believed to work by increasing the extracellular (i.e., outside the cells) concentrations of dopamine and norepinephrine neurotransmitters in the brain. Adderall does so in two ways: (i) indirectly by inhibiting the intracellular (i.e., inside the cells) reuptake of dopamine and norepinephrine neurotransmitters by brain cells and (ii) directly by pumping out these neurotransmitters from brain cells into the extracellular spaces, particularly, neural junctions or synapses. Ritalin, on the other hand, does so only indirectly through reuptake inhibition of dopamine and norepinephrine – neurotransmitters associated with motivation, focus, and happy disposition.
Perhaps because it is a mix of four chemicals and works by two-way action, Adderall is found to be more potent than Ritalin, though only marginally. But that might just mean that one has to take less quantity of Adderall than Ritalin. Adderall action lasts for 5 to 6 nours, whereas Ritalin action lasts for 3 to 4 hours.
But in no way does this imply that the efficacy of Ritalin is any less than that of Adderall. It all depends on individual response to these medications whether one should take Adderall or Ritalin. Some people respond better to Adderall, while others respond better to Ritalin; some may even respond equally well to both.
As far as the side effects of Adderall and Ritalin are concerned, they are more or less the same, qualitatively speaking. Perhaps Adderall being the stronger one may show slightly stronger side effects. But again, it all depends on individual response to these two medications. Thus, the difference between Adderall and Ritalin regarding their side effects are not clearly marked. But some preclinical data and studies on animals do indicate that amphetamine, of which Adderall is a derivative, may cause neurotoxicity due to oxidative stress from breakdown of dopamine. Not much is known about the neurotoxicity of Ritalin.