Recommendations

Both feature characters from different profession but developed a camaraderie after finding out they have the same goal. Great chemistry of main leads, both have BL undertones/censored bromance. The only difference is that one is a happy ending and the other is a tragic one.

people weak at heart and are way to emotional going on rampage. this one without turning into hideous monsters.

both set in a Japanese high school. the male lead isn`t quite understood by his classmates but when he meets the female lead that leads him to be understood.

filled with fantasy, Romance. Gods, Demons and humans. the three realms in jeopardy. along with a good bromance and a lot of action sequences

both are about a sword that can destroy the world depending on the person that wields it. only someone chosen by the sword can wield it.

it's about a power that everyone wants but not anyone can control. in smiling proud wanderer is a specific technique and in myth of sword its about a sword.

about a sword that everyone wants but now anyone can control. one is more political and the other is more about the martial arts world.

the story has a mystery and it is unravelled as it reveals itself you come to have a better understanding of the characters

they are looking for something that gives power and has been lost for a long time. the bromance between the 2 male leads is both interesting and amusing too

The only similarity is that they are reincarnated lovers and both think that the other one destroyed their family.
Both dramas are very very different from each other except the reasons above. While bulgasal is a revenge, suspense, thriller drama with a little bit of Melo and romance, "from now on showtime" is a rom-com, lighthearted drama with some ghost and revenge plot.
But both are very interesting drama. Even when Showtime is still on air i recommend it cuz its not looking like it will disappoint it's viewers, and am loving it do much.

In both dramas :
- Rich male Poor female
- Married Couples
- Misunderstanding between the main leads
- Short length series

Both series include a main character whose parents die, he is then adopted by a new family and later falls in love with his stepbrother. One of the stepbrothers in each of the series initially refuses the other brother's affection because he does not want to disappoint their family but after some time he surrenders. In both dramas, the parents refuse to accept the relationship at first, so the couple has to persuade them that there is nothing wrong about that.
HIStory4 has a darker vibe because one of the characters uses morally questionable means to get his stepbrother's love.

Best Time is the original series. If you want to know the original storyline of this special you must watch the series Best Time.

Both dramas are based on deep-seeded past family revenge plots - carried out by a daughter in one series, and a son in the other drama. Both children set-out to take revenge on both of their father's enemies - their targets the families of those enemies. One target family has three brothers, and the other has three sisters. In both dramas, the siblings are apart of the plot.

Both the dramas On the way to the airport and where stars land are based on airport romance mainly Incheon Airport
Both dramas have naive FM
I somehow get the same vibes from ML
OTWTA is a slow paced adult romance with cheating story involved