Both the Deer and the cauldron and Demi Gods and Semi Devils are jinyong's novel, tbh some of the martial art in Deer and the cauldron is from Demi Gods and semi Devils but much much weaker, even jinyong himself said it. Most of the casts are similar especial the actress are almost the same and male lead Han Dong. The director for both of this Tv series is Samson Lai Shui-Ching and he also acted as "Ao Bai" in The Deer and The Cauldron and "Wang jiantong" in Demi Gods and Semi Devils
