Truffles and mushrooms are both in the fungi kingdom, and they both contain the same psychoactive alkaloids - psilocybin, psilocin, and baeocystin being the most prominent. The main difference between them is that mushrooms are the above-ground fruiting body of fungi, whereas truffles grow underground, and are made from clumps of mycelial strands. The reason why I work with psilocybin truffles is because they are fully legal in Holland, whereas psilocybin mushrooms are not.