White magicians claim to be working in harmony with some higher ethical standard, like “the highest good of all” or will of “god” or something, they usually end up tying themselves in knots about how their omnipotent and omnipresent being made a reality that then needs humans to scurry round fixing or “healing” it, but there are ways or sorting those paradoxes out, if you’re into that kind of thing. 
Black magicians mostly just do what they want, regardless of whether or not some sky daddy appvoes of it… of course that removes the safety nets most of the time, but it also removes the limitations. JMO!
I did a long post with my definitons of Right-Hand Path & Left-Hand Path (which is a slightly different thing) in the post linked below, based heavily on Stephen Flowers’ (to my mind, definitive) book on the subject: