Both are slice-of-life drama centering on a cute, slightly wacky and naive young woman, a non-nonsense, newly-arrived male lead and other more secondary protagonists whose life gets unravelled through the drama.

While Drinking Solo centers on the civil servant field (we follow students aspiring to pass the civil servant examination and their teachers), A Poem A Day takes place in the medical field and is about a team of physical therapists.

These dramas center on a bunch of roommates in an urban setting (there is romance, drama, comedy...)

While EW centers on a bunch of guys friends who are part of the entertainment world and who run a guesthouse, AoY and its sequel centers on a group of college going girls who room together in a nice flat.

These dramas center on a bunch of roommates in an urban setting (there is romance, drama, comedy...)

While EW centers on a bunch of guys friends who are part of the entertainment world and who run a guesthouse, AoY and its sequel centers on a group of college going girls who room together in a nice flat.

Both dramas deal with the posh youth of Seoul.
Rich heir boy vs cinderella type girl and all the family drama all around.

These dramas are reminiscent of the Gossip Girl series.

In each drama, their is a girl with very good qualifications who ends up moving in a socially awakward -yet accomplished- man.
This living arrangement will lead to a marriage of convenience.

Set in the same time period, both dramas follows young individuals, their infatuations, love, deceptions and growing up.

In both dramas, a team is made up to catch fraudsters (taxes in 38 Task Force and insurance in Mad Dog).

Both the lead character are nutcase, also experts in their field (Accounting for Chief Kim and Law for Mr Jo) trying to take down a big firm rotten by corruption and malpractice.

Both these dramas center on spunky and sharp-tongued young girls. We also see their family dynamics and friendships.

One gets a feeling of melancholia while watching these girls going through first love and navigating through their youth during a time that's long gone.

In both dramas we follow the lead protagonist as he get's hired in a big company. It's interesting because we get a glimpse of how a Korean company works (conformism, hierarchy...)
While Jang Geu Rae is not qualified for the job ang introverted, Chief Kim is talented and extraverted.

In each drama, the lead heroine is desperatly seeking a husband.

Both dramas centers on socially awkward characters and their desire for a domestic life.