Although the story lines aren’t similar, the concept of transportation system (a train in Train and the subway in Catch the Ghost) is what the mystery in both dramas are based on. The killers in both dramas have a similar strategy in murders too, both having to do with suitcases...

In Rich Man, the FL works for the ML (like in WDL). The ML constantly feels familiar with the FL but doesn’t exactly remember her in Rich Man because of his “illness”. In WDL it’s a similar case.

Main characters met once during childhood/younger age, specifically during some kind of traumatic event.
They meet again many years later~

(Male leads from both dramas have similar personalities too)

Both consists of supernatural powers. Also takes place in a school environment and has a love triangle between the female MC and the two male leads. The main male lead also dislikes the female MC at first.

I DEFINITELY RECOMMEND BOTH but get ready for the sleepless nights. Best to watch this during a school break so you don't fail ur exams.

(High School Love On has a much better ending though, and is a KDrama while Super Star Academy is a Chinese drama.)