Bob, I doubt there is any difference beyond the label, current loading data from Hodgdon is on the web and it's the Hodgdon site but list 700-X as an IMR powder.
http://www.hodgdonreloading.com/data/shotgun
As far as shooting 700-X in the short ten send Scott Kittredge a PM as he shoots a lot of 700-X through his short 10's and has done so for years with issue. He'll let you what he is has been using for 1 through 1 1/4 ounce of lead.