Not only do both feature inner court politics and power struggles, but also authentic Joseon speech plus fantastic acting from the respective leads. TOTD is more male-centric and LOTP is more female centric, but both manage to showcase royal politics authentically and true to the times.
(Also both dramas share one "house" - Jeon In Hwa, who plays Queen Munjeong in LOTP (and is on the left side of the poster) is IRL married to Yoo Dong Geun, who plays King Taejong in TOTD. They're nicknamed "sageuk king and queen" because of their frequent, authentic and critically acclaimed portrayals of Joseon figures)
(Also both dramas share one "house" - Jeon In Hwa, who plays Queen Munjeong in LOTP (and is on the left side of the poster) is IRL married to Yoo Dong Geun, who plays King Taejong in TOTD. They're nicknamed "sageuk king and queen" because of their frequent, authentic and critically acclaimed portrayals of Joseon figures)