The difference between baby back and St. Louis–style ribs doesn't really have to do with how you cook them, but in the cut you start with, hill food says on Chowhound. St. Louis ribs are spareribs with the so-called rib tips removed, mike0989 says. Spareribs come from a spot on the pig next to the belly, arguably the tastiest zone of the animal (see: bacon). And rib tips themselves are beloved by Chowhounds, who consider them a delicious treat.
Meanwhile, baby backs come from the back side of the pig, near the loin, mike0989 explains. And while mike0989 prefers St. Louis ribs (they're a bit more substantial), it's true that baby backs and St. Louis ribs are interchangeable in recipes, though you might need to adjust the cooking time. Baby backs just don't stand up to long smoking—they actually come out better with less cooking, 9lives says, which is probably why they're so common at chain restaurants.
Discuss: St. Louis vs. baby back ribs
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