The black and white shamans can be differentiated very easily, because while the shaman blano relies on the forces of good and light, the black shaman rests on the strength of evil and dark.
Relying on forces of good and Light means supporting oneself with entities of high degree of spiritual progress and that is why they are in tune with the Law that governs the Universe that is LOVE.
Relying on the strength of evil and darkness means to lean on with entities charged with HATE, entities with very little spiritual progress