Both female leads find out they're connected to royalty. Both shows start off from rags to riches, then suddenly they become royalty with money. Both Female leads have this quirky way of doing things, which makes sense, as they are learning how to live differently from what they've known their whole lives.
Great love plays the first role here. In every drama of this type we also have unheard-of accidents, betrayals, lies, pain and suffering. To deal with this, the main characters sometimes have to sacrifice something more than just themselves, but also others. Will they manage to find real love? Both series strive to fulfill this prophecy.