Yosuga no Sora: In Solitude, Where We Are Least Alone., Hoshizora e Kakaru Hashi Recommendations
They are pretty much the same buuut in Yosuga no Sora, Haru(the male lead) has a sister who happens to be a delicious loli, and a loooot of fan service nearly falling into porn, while in Hoshizora the main guy has a shota(loli boy?) oni-chan, and a lot of shota fanservice -__-...
Each anime starts out with a ordinary harem lead moving to the countryside with their sibling, giving both of them a similar feel. A lot of the characters are pretty similar too, so if you like one, you'd probably like the other. Yosuga no Sora has incest and a lot more fanservice than Hoshizora e Kakaru Hashi, while Hoshizora doesn't have very much fanservice (although, it should be noted that there's quite a bit with the protagonist's younger brother...). Unlike Hoshizora, Yosuga no Sora operates with an arc system, giving each of the girls a chance with the main character. I'd say Yosuga no Sora
You have two siblings that move to the countryside. Yosuga No Sora is More ecchi than Hoshizora
In both cases the guy and his sibling move to a rural town very familiar with them in their childhood and both of them enroll in a school. Both have almost the same type of harem and female character personalities. Both contain Beach, festival etc scenes. The main difference in Yosuga no Sora and Hoshizora e Kakaru is that in Yosunga no Sora, the MC has a sister instead of a brother who is part of the Harem.