Don't quote me on this I could have the two mixed up,
but if I remember correctly, the stems have more psilocin in them, which is what psilocybin is broken down into by the body, so it might take effect a little quicker? And caps have more psilocybin which gets broken down into psilocin, although I don't think it was that much more than the stems.
If someone has the definitive answer for this, it would be most appreciated to add it into the discussion.