SWW,
You're right - the cut is the same (and preferably with a fair bit of fat). But the Jewish-style brisket isn't corned (unless you're specifically having corned beef). Rather, it's slowly cooked, either on the stovetop or in the oven. Everyone has his/her own recipe. I pile mine on top of tons of sliced onions, season it with garlic, cover the pan extremely tightly, and let it cook very slowly on top of the stove - not till it falls apart, but until it is as tender as possible. For Passover you don't use flour, so I add a little potato starch to all the oniony, beefy liquid, and that's the gravy.