1. Although the phenomenon of withdrawal has always been the crucial physiological Leng for distinguishing addictive from nonaddictive drugs, it has become increasingly evident that not all regular heroin users experience withdrawal symptoms.
I remember something being said about distinguish between X and Y and distinguish X from Y. The former seeks to contrast two things that are very similar: Ex: You can't even distinguish between a rabbit and a cat. The latter contrasts two things that are opposites of each other. Ex: You can't even distinguish right from wrong. In this question, addictive and non-addictive are opposites, so you want to use the idiom distinguish X from Y.