Same melodramatic vibe; same story of two individuals meeting and getting along but soon separated by tragic circumstances only to meet later in their lives; equally amazing soundtrack. By the end, only the seasons and the musical compositions in the titles are different.

Same concept (recycling old folk tales), different vibe. Cinderella's sister twists around the story of Cinderella, making you sympathize with the sister in a melodramatic tale. Alice in Cheongdamdong gives Wonderland a Korean name, and the White Rabbit a very nice human body in a not-sure-if-comedy-or-what story.

Same concept, different vibe. Who are you is on the suspense/action side while Master's sun is on the comical side, but in both cases, girls see ghosts and fall in love. In which drama I'd rather be? Who are you. The ghost might be freakier, but at least I'd kiss Taecyeon AND Kim Jaewook.

Same story, different time period. The two little girls are equally cute, but I choose Lee Jun ki a thousand times over Lee Dong Wook, sorry!

Same actor, same story, same vibe. Only the cast is different. Moral of the story: if you're looking for a dark, vengeful plot, always look for Kim Nam Gil.

Same lead actress, same story of strangers engaged by force/circumstances, same vibe. The dudes make all the difference.

One of the standing blocks of QSD is the script, the deep conversations between "good" and "evil" characters, and how much the drama made you think of politics, justice and morality. Tree with Deep Roots also has the same ingredient.