[sowbug]

That's generally right for cubensis, except that variation from fruit to fruit is generally greater than the variation from variety to variety. A notable exception is so-called Penis Envy, which is established to be significantly more potent in psilocybin and psilocin content. That variety also has an interesting origin story: https://www.youtube.com/watch?v=QRArM5Ev4EE

Other Psilocybe types, such as semilanceata, azurescens, and baeocystis, differ in that they have more or less of other compounds such as Baeocystin, which some believe have psychoactive effects.

Many people report nonlinear responses to psilocybin/psilocin dosages. For example, 5 grams of dry cubensis is more than twice as strong as 2.5 grams. So it's understandable that stronger varieties have qualitatively different reputations than weaker ones.