The Light/Dark Energy Spectrum is something that each seller classifies differently. I often just call it the Energy Spectrum. Allow me to explain how I see and interact with it. I see the spectrum as White Arts, followed by Gray Arts, followed by Dark Arts, and ending in Black Arts. For me, it is a literal spectrum, like color, where energies shift in lightness or darkness depending on where they sit on it. Some sellers classify beings based on behavioral habits, but I classify based literally on how I feel them energetically.
White Arts is the brightest part of the spectrum. To my understanding, there's no "limit" on the width of the WA spectrum. If it were to sit on the left side, should you continue to go left, the energy would become blinding and even nauseating. White Arts energies and beings do not cause harm, save for situations like self defense. They tend to be void of selfish motives and are not ordinarily of a self-centered state of being. However, White Arts is not necessarily synonymous with helpful, as our instincts would try to paint it with goodness and love. There are beings that are WA because they will not harm and they will not take but they may also choose a life of solitude.
Gray Arts follows White Arts on the Spectrum. Some sellers either do not recognize Gray Arts or will merge it with Dark Arts, the following part of the Spectrum. I do not do this because to me Gray Arts has a very specific energy signature that has not quite lost its White Arts sheen but is also not dark enough to be considered true Dark Arts. It is, for a lack of a better description, a gray area that exists between the two. Energies that fall on the lighter side of White Arts feel more like White Arts but maintain their "Grayness" while those closer to Dark Arts feel darker but still feel a little too light. At its center is true neutrality, and I've come to find these energies and beings to be rarer to find, but this may be because I'm less attuned to Gray Arts. Unlike White Arts, Gray Arts beings can cause harm out of selfishness, but it is normally for a good reason. Many powerful protection beings lie in Gray Arts because while they have the lightness of WA, they also aren't afraid to get a little dirty.
Dark Arts follows White Arts on the spectrum. There's a very clear line for me when GA has shifted into DA. Dark Arts has an undercurrent of a certain gritty yet velvet quality that reminds me of plunging into a dark pool where the floor is gently sloped. DA feels the most vast and complex to me, but this is probably because I resonate stronger with it. Dark Arts beings can act with selfish purpose and can cause harm, depending where they lie on the spectrum. Beings closer to GA are less likely to be selfish while beings closer to BA, the last part of the spectrum, can be enormously selfish and harmful. However, just because a being can be selfish or harmful, that does not mean it will be selfish or harmful to you. It depends on the being. I had the honor of conjuring a being who was almost BA, but still DA, who was savagely ruthless with things she deemed enemies but was highly protective of her human companion. Dark but sweet beings exist, but so do dark but threatening. Also, in the mainstream "Dark Arts" has a certain reputation of being evil, in concern to magick. First, there is no true "good" or "evil" when it comes to magick. Second, dealing with things of a Dark Arts energetic nature is a common part of human life, so it is not as exotic or nefarious as it would seem. In fact, Dark Arts is ordinary. Much of the animal kingdom is Dark Arts. Bird eat bugs to survive, cats eat bugs and birds. It is the duality that permeates throughout the universe. As human beings, we exist on the Dark Art Spectrum, with some of us being lighter or darker.
The ill reputation of Dark Arts, should be applied to Black Arts instead, the last part of the spectrum. Black Arts is the big bad because it's just a total drop off into a hole. There's no mistaking BA energy, and even though BA is just a small jump over from DA, it is not a smooth transition. For me, there is no confusing very dark DA energy that's close to Black Arts on the spectrum with actual Black Arts beings or energies. It feels penetrating and toxic. Black Arts is the energy of decay, and energies and beings belonging to this will always seek to initiate that process of decay. There are many more skilled than working with BA than I, but this is my experience with it thus far. BA should avoided by beginners at all costs.