Same writer and director. Plus the stories have simmiliar cute and light feeling with main guys chasing after female leads.
Both center on a relationship that is severely tried by public status and the need to keep it on the down-low, especially in the early stages. Both male leads are older and zany, with a touch of cool; they also each undergo a physical style change which alters their appearance drastically. Both female leads are tough yet inwardly vulnerable, reluctant, and have complicated family lives. There are hilarious assistants accompanying the male lead and somewhat pitiable, yet occasionally nasty second leads. Mix in cruel Netizens for added similarity.