Both xianxia dramas where protagonists have 3 lives, they grow up and after a very long time they understand each other.

Just an Encore is more slice of life and Hana Yori Dango is a little more "unreal" because students are too much rich lol.
But both are great in their own way and female lead doesn't prefer the most perfect, quiet , serious and sweet guy, but the one with whom she quarrels more!
At first they don't get along very well, but as time goes by, the guy conquers her heart little by little.

Both have many political schemes. smart protagonists and you always crave for more eps!

In Nirvana in Fire, the protagonist succeeds in every situation while in Royal Nirvana, the main character fails a lot and you suffer more when you watch it.

Both are excellent in their own ways :)

Both protagonists are very smart, come back with different names and plot a revenge against all people who crossed their ways.

-In modern times, Jin is a doctor and Ken is a chef of a french restaurant.

-Both travel back in time to japanese feudal period and have to improvise with techniques of the past, using their knowledge from present.

-In both dramas the protagonists have a parent who dies in a hospital with many doctors who care more about research and money. They grow up, change name and go back to the same hospital to look for justice.

-In Surgeons the main point is not the revenge. If you really want a story about revenge in hospital, watch "Alice no Toge".

-In "Alice" the protagonist takes down each one of the nurses and doctors involved!

Both dramas are about women around 40 with their struggles about marriage, carreer and children. Also, both have Naohito Fujiki in the cast.