Both have cooking as base story
similar vibes in both dramas
cooking shows in both dramas

similar vibes in both dramas (idk even the soundtrack gave me similar vibes)-
sick male leads in both
exes reunited and have a hate-to-love relationship

same vibes
nostalgic vibes
I swear it's just literally based on vibes trust me on this
there's no time travelling in road home though

After watching the trailer the whole body swap plot is very similar in the two dramas
Both have cold male and bubbly female characters too

Lee Se Young is the main Female Lead in both dramas
Somewhat similar vibes but are pretty different plot-wise.

The leads travel back to the past in both dramas (although for separate reasons and through different means i.e. photographs in blue birthday and cell phone in first love again)

Girl dresses up as a guy (although in the coffee prince the girl is technically a tomboy- but regardless i get similar vibes)

Set at the same time, in the same era of Republican China, and have a similar theme of bloodshed. Gives revolutionary vibes for both. Both have the spy aspect to them.