Recommendations

Both are romance historical dramas with happy endings. Similar part of plots - evil girl steals identity of the good girl and the main character keeps looking for her.

Same era and historical characters, beautiful love story, awesome music and acting.

The relationship between the main leads is similar. The girl is kind of obsessed with the guy and he starts to develop feelings for her.

Both dramas are about young skilled surgeons who treat gangsters/criminals illegally and keep it a secret. They both started to work for those patients because they're in need for money to heal a relative.

Both medical dramas about skilled surgeons with similar personality's who work at a hospital but also illegally treat gangstas/criminals secretly for money.

Both dramas are historical and the female leads are disguised as a 'flower boy', even though in Gu Family Book is unitentional.

One of main characters is a cop, and the other help the police.
There is a mystery from the past, some connection between main characters. Plot is mainly about crimes, investigations etc
. We have romance with good chemistry.

The only difference is that in Girl Who... female lead have supernatural power - she can see smells :D

Both main character matures a lot from the beginning till the end and they both tried to adapt in a place different from where they used to live in. Both talk about family-related matters and Gochisousan has more romance.

Self explanatory^^ they both have the same story line and both of them will no doubt make you brawl like a baby lol.

Both have a strong female lead and employee among incompetent people. There is also humor and last, but not least skills.

BOF has one main girl and 4 hot guys. (Gu Jun Pyo from BOF and Fang Ting Hao from TWG are sooo hot)... anyway you should really give this drama a try!!!

Both protagonists don't simply do their jobs for the sake of it, but more for the pride they enjoy at doing the rightful things. They go far beyond their jobs description, especially when they feel somebody has been wrongfully accused.
Both have change jobs position or location, and their arrival mark the beginning of significant changes in the company image, due to their involvement in a different case day after day.
Hanamura Daisuke is a lawyer while Hanasaki Mai is a bank employee.

Jig Jang-ui Shin is the korean remake of the japanese 2007 drama with more episodes

Both deals with north korean spies. And in both dramas the female lead has two options: either deceive her boyfriend and continue as a spy, either betray her boss and fight against the side she was.

Both have some little narration here and there by the protagonist. Have similar style of humor and the characters are flawed yet lovable.