Both dramas focus on mending their relationships with their mothers.
IDWTBWY is about fl understanding her mother by time travelling while TGBM is about the mother understanding ml when he gets an accident.

In Don't Disturb My Study, FL shifted classes from existing class to a new class after a long time while ML does the same in The Big Boss S2. In DDMY, the group of friends cheer FL all along, while the same happens with ML in TBB S2. In both dramas, the leads build a strong friendship and bonded closely with their existing class very much.