Both these dramas are gripping thriller that will keep you on edge.
Murder, mystery, friendships, a lot of drama and bitterness are to be expected.

Though the tone and atmosphere of these drama are different, they both deal with the lives of a group of middle-aged friends.

Lady In Dignity is more about a set of female friends from Gangnam while Graceful Friends is about a set of friends who have known each other since college.

The similarty lies un the fact that both dramas center around middle-aged men.
AGD is lighter than GF which has a murder as a pivotal plot point.

The plots aren't similar but in both these dramas, the female leads are quite antagonistic and bitchy (evil mistress and evil daughter-in-law). It's different from dramas starring meeker heroines.

They are still likable though.

Hell hath no fury like a woman scorned....
These dramas are centered on middle-aged women who decide to avenge themselves against people who wronged them.

These dramas deal with middle-aged women who go through crises be it financial or marital.
These dramas are also quite realistic and gritty.

Both these dramas show quite realistically the struggles of some of the MC making her first steps on the professionnal world.

Realistic dramas showing the daily life of Korean people ar work. In Black Dog we follow high school teachers and in Argon the employees of a TV chanel.

Drinking Solo and Black Dog both centre on the educational system on South Korea.

While in Drinking Solo -which has a lighter feel- de follow teacher in an academy for aspiring civil servants, Black Dog -which has a darker ambiance- is about the daily life of teachers in a high school

In both these sageuk, the crown princess/queen selection is a focal point of the intrigue.
The crown prince/king prince influences on the selection process because he's already smitten.

These dramas have for leads a North Korean and a South Korean who will be seen having a romantic relationship and takes place in both countries.

In both these dramas, one of the lead works in the North Korean army while the South Korean is someone who lead a priviledge life in South Korea (a prince in K2H and a cheabol heiress and CEO in CLoY).

Both dramas deal with Palace intrigues involving the crown.
The theme of cross-dressing is also dealt with.