The series are sequel of the movie. So be sure to watch the Drama series after the movie or it will spoil a lot.

Both have funny characters with serious cases, also both dramas partners are great combo (even if in Bitter Blood they say that they hate each other while in doS they like each other openly) also Bitter Blood is more realistic while in doS have some unrealistic, "Manga/Anime" style moments (although it's only few moments)

Both have fake kidnapping, the Issen is more serious while Mou Yuukai is more mysterious and romantic.