Both have main female leads that are smart, cheeky, and good a solving mysterious.
Puzzle (2008)
Similars
Both dramas are from the 2000's and about mystery solving.
Both have a strong female lead as the main character.
Whenever I think of puzzle I think of this series. Maybe because it the year they both were release at the same time? The theme are similar, it funny and enjoyable. Puzzle is a team of high school boys who solves mystery for their strange and bipolar teacher. Whereas the four sisters are a group of sisters solving the mysteries.