In a nuthsell:8s overuse their instinctive center, which haves to do with going with your gut, physical, visceral stuff. Instinctively knowing what to do and do it. 5s are opposite that way, they do not want to "do", their instinctive center is underdeveloped, they stay within their own minds and conceptualize, they feel like kings and queens in their own minds, whether if they are really smart or not, although they usually are ime. You'll usually see 5s as kinda clumsy, or at least uncomfortable in their own bodies.