Ethical Atheists strive for esoteric knowledge and understanding of life and it could be one reason why they reject the popular notion of God! However with a theological system although it could have a narrower view on life, its biggest and most important advantage is can be taught and understood by a wider range of people, thus the positive effect on society is wider and more understood. Also there’s nothing stopping an ethical Atheist from applying there ethics to any current theological system, people with esoteric understanding usually do try apply there knowledge to current theological systems. So I guess the main difference is the inability for an ethical atheist to spread and teach there knowledge to wide range of people. After all an important part of life and living is not just learning but teaching.