Both are about a fairly normal high school girl and a guy who has no sense of social norms and does all sorts of crazy stuff around the girl while shes in school. Also in both there's a hint of romance between them.
Two of the main similarities between these titles are: large and varied cast of characters, and narratives that mainly transpire within a school setting. Both titles also mainly feature comedic aesthetics, but sometimes mixes in elements of romance, drama, and sometimes even action.
Similarities include: a varied cast that allows for comic, romantic, and combat elements to transpire in the narrative; elements of sci-fi/fantasy intertwined in its seemingly slice-of-life style; and a prevalent sense of comradery amongst a group of friends.