They both same because :-

-the ML is an idol
-the FL is ML 's assistant
-they fall in love with each other

Both story has the same plot:-
-high school lover separated and see each other after so many years no see.
- clever ML with high mark on examination
-FL always fail in the exam and with the help of the ML, she get high score.
-poor FL

In the both drama

the character name is almost similar

It also have the same plot, and ghost story

It also about a human fall in love with a ghost

In Both drama :
- two princes fighting for a girl
-the FL sister love one of the prince and hate the FL

The similarities :-
Almost all the characters act in both drama
It also about arrange marriage
Their screenwriter is also the sama jin yuan yuan

The both is the same because of

- FL from the present time and go to the ancient time
- in the ancient time FL is not the actual heroine
- Both FL is third princess
- Both Second Prince / Princess is not the ruler real children

Because 3 of the actor in this drama played in the love by hypnotic... The story is quite similar too