Both are very similar in that both main leads had something going on when in school. However, due to circumstances, they lost contact only to meet years later when they are working adults. Male lead is also the cold type that doesnt love to talk while female lead is bubbly and innocent. Both shows have flashbacks of what happened in school and how they will progress in present time. The young female lead of My Sunshine is the main female lead in Le Coup too.
The plot and the main characters are quite similar. However, not completely the same. Also about a prince marrying a wife but in this story, the female protagonist is already the princess but with Naughty Princess they have to overcome some obstacles. Also about the female protagonist time travelling from the modern world to the past. This story also talks about 3 princes with the eldest and the second eldest fighting against each other for the throne with the 3rd prince being on the same boat as the second prince.
Both dramas about the female lead finding clever and unique ways of solving problems.Both seem to constantly be involved in trouble and always need the male lead to save and protect them.Both male leads of the story are basically crazily in love with their partner and would risk their lives for them. Both also involves harming/poisoning each other to indirectly save each other.