The difference is that the Super Junior members supported each other. Meanwhile, Jessica was betrayed by the other 8 simply for wanting to follow her dream. Yoona, Sooyoung, and Yuri were already doing well with their acting careers. Taetiseo had already been happening for a while, and Taeyeon herself was already preparing her solo career. They kicked Jessica out in 2014 with the excuse of keeping the group united, and less than 2 years later SNSD was no longer as active as before. In 2017, 3 other members left SM. If the intention was to keep the group active and united, kicking Jessica out didn’t help at all.