Both are buddy oriented, Action dramas, focused on some type of martial arts. They also explore some contemporary social issues.

Fight is oriented towards MMA, with one primary protagonist; Bloodhounds give us two.

Both are coming of age stories in which young men have to mature and take hold of power and responsibility that is both difficult, meaningful and have personal stakes.

Both are coming of age stories in which young men have to mature and take hold of power and responsibility that is both difficult, meaningful and have personal stakes.

Both are long form family drama that revolve around secrets within a family, and their attempts to deal with their pasts, and the choices they are making and the strain that result from them.

Both make use of similar tropes, and due to the nature of the endings, I think one inspired the other.

Both explore Korean modern society and culture through the lens of family and the effect the demands of "modernity" has on family and culture. This is explored through the perspective of adult children seeking love, fulfillment, status and financial stability; and how family and past choices aid and hinders this quest.

Both explore obsessive love, marriage, loyalty, friendship, betrayal and infidelity. Love Twist strikes me as looking to be a little more nuanced with it's villainous characters; and also created in me a greater level of discomfort offending my sensibilities.

Both are family centered, Romantic Drama/Comedies allowing us to follow a transitional period in a family in which the children need to reach a new level of maturity; and the parents deal with unresolved issues and the challenges of aging.

Both are action oriented stories with a focus on friendship, loyalty and mastering the classical virtues (Prudence, Temperance, Fortitude, Justice). This mastery being expressed in martial prowess; allowing the main characters to transcend their psychological and social "prisons".
As for differences Fight is far more subdued; it takes longer to tease out it's themes; the supernatural isn't explicitly expressed; and humor more subdued. In the same vein vice and virtue in the characters is expressed in a more subdued manner in fight.