Both dramas feature an older rich woman/younger poor man dynamic and both dramas have a female CEO/boss who own entertainment companies (books, games, etc).
Although the tones of these two dramas are completely different, both dramas deal with mental health illnesses and they're effects on the character's lives. Woo Joo, the main character of "Soul Mechanic" deals with anger management issues and finds it hard to control her temper just like Hwi Oh does in "Mad for each Other."
Both dramas center around college students and college life and both dramas have a storyline involving people living together as housemates. Although Age of Youth has more drama and conflict, both dramas are very slice of life and the romances are similar.