The colour of fungi does not determine their potency. Potency depends on the content of psilocybin, psilocin, and baeocystin, which determines the strength of the mushrooms. Colour variations are due to genetic differences.
Some pale varieties may be leucistic or albino. Leucistic strains are not true albinos because they can still produce pigments. These colour variations are fascinating to mushroom cultivators as a hobby.