Take the intersection of two sets

 List<Long> departmentUserNos = departmentVOList.stream().map(UserDepartmentVO::getUserNo).collect(toList());
 List<Long> postUserNos = uo.stream().map(UserPostVO::getUserNo).collect(toList());
              
  //  Extract intersection data 
 List<Long> collect = departmentUserNos.stream().filter(postUserNos::contains).collect(toList());

// Take the difference set 
departmentUserNos.removeAll(collect )---> The rest in the set is departmentUserNos Unique 

 Empathy ：
postUserNos.removeAll(collect ) ---> The rest in the set is postUserNos Unique