Phil, Don't think there is any difference in them both lower resistence maybe a different manufacturer not sure so many change's to make things better...In a perfect world all carto's should fit on all batts but sometime's thread's on batts need sanded lightly or carto's threads aren't right not sure though if that's your problem.There is some video's showing how to remedy these problem's...try searching on forum for them.As far as I know the only difference in the 2 cartos is the juice if you get pre-filled.