User blog comment:EmpyreanSmoke/Seraphim and "Common" Angels/@comment-26130316-20150221000237

There is a hierarchy in both Heaven and Hell. Seraphims (Seraphs for short) are just under Archangels which are the strongest. It has already been proven multiple times that there are lower and higher ranking Angels and Demons. Take Castiel for example, he was once a "normal" Angel. Once he was killed by Lucifer, God resurected him and promoted him to the rank of Seraphim. It doesn't make them a different species, so I don't know what you're getting at. They are all still Angels, the only real difference is their rank. When an Angel is promoted it gains more abilities as well as impoving their current ones. Most of this applies to Demons as well, so there you go.