Both are rivals to lovers dramas with great chemistry between the leads. FLs are independent and tough. MLs are arrogant but very sweet to their FLs. Side characters in both dramas have cute storylines as well. Both dramas sweetly portray the leads' commitment to each other and relationship evolution even after they get together.
Both dramas have pretty similar relationship dynamics with bubbly louder FL and soft quieter ML. Come and Hug Me is much darker/more melo even though it has some funny moments; Into the Ring is much more comedic.
IONTBO is definitely a much more romance based show and Flower of Evil focuses more on the crime/thriller aspect (as of ep 6). Both shows have dark characters with ambiguous morality and motivations. Childhood trauma/violence and its role in influencing adult behavior also plays a major role in both shows.
Both are thrilling, fast paced crime shows with incredibly morally ambiguous characters. Extracurricular focuses on younger high school aged characters while Flower of Evil focuses on an adult married couple.
They have the same screenwriter, which explains why I loved the secondary characters so much. The plots are also centered around complicated family dynamics.
both are short and sweet, the second seasons of both webseries in particular tackle changing relationships with childhood friends
Both have main characters with ambiguous morals/motivations/psyche. Both (so far) manage to keep their anti-heroes likeable while not toning down their darkness. Extracurricular has a much more intense and fast-paced thriller plot, while IONTBO (so far) has a more leisurely pace.