Okay, I finally got around to calling Mossberg. The tech rep I spoke to explained it to me, let me see if i get this right! The accu-chokes are not extended past the barrel. That's the main difference. The X-chokes are extended out the barre for better range/patterning. He also said that their is a wider variety of chokes available with the X-chokes. And the big question "will the X-factor shoot steel?". YES it will. In fact the X-factor was designed more for waterfowl with the extended tubes. My only question that did not get answered was, will accu-chokes work in the X factor barrel. Again this is what the tech said.