Similarity? How the male lead is sick or having family members opposing and yet the romance are going strong. Good medical case study for you to study and learn about from the perspectives of the patients too. Perhaps only in drama, can we see ill-ed person having a lasting romance.
Similar plots in the fact that both male leads have mental illnesses and are proving themselves to be more than just their limitations. The rest of the plot differs on the other hand. Good Doctor said about just that being a good and capable doctor despite mental and social "limitations" and Decoded is proving hat even though he can't at the beginning he will improve himself and show that he can be great if not better than those without his condition. I fell in love with both leads and these roles show just how great they are as actor
Do you like medical dramas? Would you like to see Joowon as a doctor one more time? Then you must see this one as well. But, the both characters are portrayed totally different from each other, with Joowon's perfect acting skills..