Kyo and Fu have very similar personalities and appearence. They are a bit clumsy and some times not enought smart. Also the two stories are set in some kind of villages. Finally in both stories the protagonist has lost a parent.
-Both share the same atmosphere.
-Both anime focus on the non romantic relationship between siblings (In Chocotto Sister the little sister is not related by blood to her older brother though) and how characters care for each other. In both anime some of the problmes the characters face are some misunderstandings and sometimes lack of mutual trust.
-Both have cute and heartwarming moments.
-Both have super cute little sisters.
Just keep in mind that Chocotto sister has more fanservice (nothing like To love ru or any other ecchi anime) and may not be as suitable for children as Binbou Shimai.
both pretty much have the same thing going on: sisters only having each other to depend on, money issues, arguing and making up, and younger siblings worrying about the oldest leaving them. each are enjoyable series that will make you either laugh or feel sad depending on the situation.
Both Slice of Life and involve older siblings who work to take care of their younger siblings, although Himouto! Umaru-chan is way more on the comedy side, they both still share the same kind of relaxing feeling you get while watching them and also the same loving relationship between siblings.
Both stories centre around a pair that live alone together and, despite their moments of drama, generally have a pleasant, feel-good tone that keeps one in the back of my mind whenever I watch the other.