In snowman both the sisters fall in love with the ml while in autumn shower it is best friends. In both dramas the leads face criticism for their relationship and struggle to be together. Difference is that in snowman, the sister doesn’t wake from her coma while in autumn shower the best friend does. Snowman is a bit more light.
They both have similar vibes (tsq being more tragic). In both dramas the leads meet when they were younger, became friends, and suddenly lost contact. They both meet in the future without realising who they are. The both also have a similar age gap.