We all understand what the world in general means by "magick" and "medicine", but in the Native American tradition the line is anything but clear by definition.
Medicine, to a traditional Native, is wholistic in the sense that the mind, body, and spirit are all treated. When we use a particular plant, for example, the physical value is every bit as important as the spirit help of that plant.
Also, magick to a traditional Native, is generally accepted to be the Natural Way things are. Nature provides through the elements, plants, trees, animals, etc., and when that which is provided is mysterious in it's appearance and purpose, we simply accept it. This is magick.
Hope this helps.