One of the most reliable ways of separating the two is by the twig. The first pic is that of a young Kingnut whose bud is still green. With age the outer scales will darken, and the inner scales will stay white, just like the second picture. The Kingnut has a twig that is tan, beige, or flesh-tone, sometimes with a speckling of orange. The Shagbark twig is dark brown and Clint Eastwood, or "dirty hairy".