Do drugs affect all users the same way?

No. The impact of drugs is deponent on the users mental and physical health, other drug interactions and genetic make up. An interesting case is heroin which was originally though to be a safe painkiller with no addictive nature as all the initial test subjects were "immune" to that effect. Even alcohol has a folk history of different impact - we've heard of mean or amorous drunks and people that can function well after a binge while others fall asleep after a single shot.