Both dramas deal with mental health issues and how they impact the interpersonal relationships throughout the main characters' lives.
Both have supernatural elements and a strong yet vulnerable female lead. In both the couple has to overcome their differences in station but both our male leads love the female lead first. Our leading men also both have memory loss.
Both dramas deal with the harsh realities of life and how personal struggle can lead to positive growth.
A Korean Odyssey is pretty much the same drama as Goblin. All of the major plot-points align exactly. The only difference is that Goblin is even better than A Korean Odyssey.
Both dramas center around more mature couples that have to overcome the odds to be together. Emergency Couple is funny where Faith is serious but both had very unique romance plots in my opinion. Both are also medical dramas.