BB,
The shorts are, well short, the brass is shorter. Bad part is they won't feed out of a magazine of a bolt action. The CCI quiets have basically just a hot primer charge so they are quiet and being full size long rifle cases they feed easily. They are accurate also just hard to find. All .22 are tough to get now but those more so.
Like DRP said the subsonics are quiet, much quieter than a CB short. About as loud as a cap gun. The Marauder is MUCH quieter than the quiets lol.....you basically just hear the hammer fall....from 50 feet away you would not even hear it.