There used to be 2 organizations called the NCCB (National Conference of Catholic Bishops) and the USCC (United States Catholic Conference). The former was the bishops proper, the latter was more lay folks (I think). The two were effectively merged in function much of the time. With the changes required of national bishops’ conference some years back, the USCC part pretty much faded away and the resulting organization changed its name to the current USCCB (United States Conference of Catholic Bishops).