In both dramas, Fl's family is wrongly charged of treason who then takes the charge of saving the family. Ml is in very powerful position and tries to help fl.

Both have ml as a famous celebrity
Sort of office romance
Both have Enemies to lovers concept
FLs are strong

Both are my fav historical dramas… the red sleeve gives the same vibe as scarlet heart… ML first falls in love and pursue FL…. FL are court ladies in love with the future king …. after both leads in love with each other, they cannot marry because of political or personal reasons… the intensity of the scenes between lovers go higher as the end of dramas approach….

Similarities:-
Both dramas have Song Joon Ki as ML
ML is dark and secretive
FL in both dramas are competitive and independent
In both the dramas, the FLs avenge their father’s death
Both dramas involve a conglomerate
Difference:-
In Vincenzo, ml and FL fight against the conglomerate while in nice guy, FL the company’s rightful heir who wants to take her position

Though I haven’t seen D-day but after reading the plot, all I thought about was of descendants of the Sun… in dots too, the story revolves around doctors(and soldiers). A major part of the drama depicts both the groups dealing with a strong earthquake in Urk