User blog comment:ImperiexSeed/Supernatural Mysteries/@comment-3045936-20120409230825/@comment-3045936-20120410014949

By Hellish Creatures the Salute to Supernatural Season 6 explained this. In the series monsters normally only have shapeshifting powers in relations to their lore, Vampire's teeth, skinwalker morphing, etc along with enhanced physical strength. Very few monsters of Eve's creation has any kind of real magical type of powers like the crocotta's soulsucking, the Shtroga sucking the life force out of children, the khan worm's monster possession, or dragons heat generation.

Hellish creatures the whore, hellhounds, deava's are creatures/monsters that are used by Hell in someway and aren't of Eve's making for Purgatory isn't their afterlife. The only possible way a monster's soul could go to Hell is with someone like Crowley forcely bring them there. As explained as their power could help him to control Hell better.

Also, according to Salute to Supernatural 7 it states that Lucifer wasn't the first thing in Hell that there were spirits there already but nothings as powerful as lucifer or the demons he would make.

Its confusing and the Salute tells you things that makes you go Huh? But according to the last thing about this topic they said think of all of Eve's creatures as mutated superhuman freaks. Anything that isn't an Angel, demon or something connected to Hell or the Apocalypse, deity, fairy, levianthan, or ghost is Eve's child.