far apart;utterly different ? 真真一個娘肚子里跑出這樣～的兩個人來，我想到那里就不服！ (《紅樓夢》705) It really and truly passes my understanding how one mother could bear two such utterly different children!
天懸地隔tiān xuán dì ɡé
比喻兩者相距很遠(yuǎn)，差別極大。be separated far apart, far apart, utterly different, hang apart as heaven and earth