Both Leads are characters out of time or in a time loop. They are aware of future events and are working to prevent shadowed doom.

Both has romance that spans through time

both couples get together quickly

Both dramas are friends to lovers and the pacing and style (the slice of life feel) are very similar to each other

The main casts of both shows are both PDs and work in broadcasting so there is a lot of behind the scenes scenes to watch.

Both Lead couples were friends for decades before becoming lovers. Both are mature couples (the leads are in their 30s).

The Male leads are very protective of the female leads in both dramas.

Both daily dramas have the same format with similar plot. Both FL are orphans who discover abandoned babies and raise them as their own.

Blow Breeze and Young Lady and Gentleman has the same writer so viewers will experience the same great beginning with a lovely story telling only to be overshadowed and nosedived by ridiculous parents and subplots.

Same style

This drama could be considered an introduction to King Yeongjo of Joseon, grandfather of Yi San. This prelude can explain many of the turbulences that are depicted in The Red Sleeve, King Sukjong effected many changes that impacted Yi San's rule

Both stories are set in a college life setting.

Both female leads misunderstand love but are very open to skinship.
Both Male leads are patient while their counterparts shenanigans because they are in love.

Main protagonist are searching for what they want out of life and figuring out what love means to them

Childhood friendship that develops into romantic relationships where both female leads understand their love with the help of strong second male leads

Both shows portray the advantages one has when born into wealthy family and how those young chaebols often take it for granted the opportunities they received. It also show regular young people becoming successful despite their low background and depicts friendship between the two classes.