Both are light historical dramas of identical short length. Both FLs are doctors/have medical skills, and both MLs have personality "quirks" (poisoned so they act childlike or two different personalities and memory loss). The FLs try to cure the MLs, the two soon fall in love and live together. Both dramas have a similar feel/tone.
The actress that plays the female lead is the same in both dramas. In Dear Herbal Lord, the female lead is the daughter of a doctor and the male lead is also a doctor. In this drama there's a kind of memory loss for both leads and also some kind of "double personality", as the body of the female lead becomes the home of two different souls.