Well, with the Inferno, another ball I have not thrown, but I have seen many people throw one, including the same guy that has the Thrash and X Factor. His Inferno is drilled a little stronger.
When he throws on medium, which is about all we bowl on in this one house, these are the reactions I have seen out of the 3---
-Thrash is not quite a long and flippy as the other too. More even rolling for a pearl.
-X Factor, goes extremely long and snaps real hard in the backend.
-Inferno, rolls up sooner than the X Factor, but maybe half a foot to a foot and a half later than the Thrash. It is more violent off of the dry than than the Thrash, but not a violent as the X Factor
All three of three of these balls can smack the hell out of the pins. The difference in reaction between them all is the coverstock. The Thrash has the stronger of the 3 in coverstock, whereas it may have the weaker core of them.