the difference in comprehension of the types would fall within the boundaries of the spiritual aspects of diamond approach. they explain the fundamental virtues, fixations, instincts, holy ideas, and passions of each type. unfortunately the best advice i would give to find out about it is to look into a book by either a.h. almaas, or sandra maitri. i bought sandras book "The Spiritual Dimension of the Enneagram; Nine Faces of the Soul." and i haven't read any of Almaas' yet, i've got some in route right now. you can also check out ahalmaas.com if you're interested in reading excerpts from his books, or reviews/generalizations of DA. it's got alot of great stuff on there including lectures, videos, glossary for the terms. i'd suggest you start there. i have a pretyped intro into DA i wrote myself which i could send you also through pm, though it should probably be updated but let me know.