They sound a lot different I find,Ja has a more scratchy voice,and DMX is more gangsta.But if you can't tell them apart by voice then their is another way.Almost all of Ja's new stuff he says Murder Inc,and has a girl singing the majority of his choruses.As for DMX,he does that bark,and tends to do mostly gangsta rap.Thats a simple way to tell if you can't tell their voices apart,but I think they both sound destinctivly different...