Amphetamine like adderall,vyvanse are weaker because they do not have a methyl group. adding a methyl group to amphetamine makes N-Methylamphetamine. a Methyl group makes it much more potent therefore you need less to get high and it is much more powerful.
for more info go to
https://psychonautwiki.org/wiki/Adderall
https://psychonautwiki.org/wiki/Meth
