Same supernatural concept with different side stories between human and spirits.
Male Leads are immortal.

Supernatural/fantasy element during republican era.
Both have male lead that had lived for a long time (immortal). They also tried to help others and vanquish evil spirits.

Queen Lau reminds me of this old drama My Bratty Princess.

Both FL is funny and totally change the atmosphere of the palace once they entered.
Another thing is they're sassy and not easily bullied. They know how to fight back.
Both FL is the daughter of a high-grade official in the court.
Both assist the emperors and give them a whole new perspective on how to govern the country.

Both have supernatural elements set in the Republican Era.
Both are episodic as in main leads encounter many other stories of humans and spirits before eventually leading them to the finale of their own.
Some of main leads' pasts are shrouded in mystery.
Both have a romance that spans over a thousand years.

-Same concept. Twin Sisters identity swap.
-Younger sister assume the identity of talented older sister while older sister mysteriously goes missing.
-Younger sister fell in love with ML

Both are set in China Republican era, the Sino-Japanese war. Stories that focus on the relationships surrounding a prominent family during the time. Both have obsessive/stubborn main leads and love triangles.

Both are set in China Republica Era. Both have an angsty love story about love and betrayal. They also have misunderstandings between the main (married) couple.