<P> Several different types of ribs are available, depending on the section of rib cage from which they are cut . Variation in the thickness of the meat and bone, as well as levels of fat in each cut, can alter the flavor and texture of the prepared dish . The inner surface of the rib cage is covered by a layer of connective tissue (pleura) that is difficult to cook tender; it is usually removed before marinating or cooking . </P> <P> Baby back ribs (also back ribs or loin ribs) are taken from the top of the rib cage between the spine and the spare ribs, below the loin muscle . They have meat between the bones and on top of the bones, and are shorter, curved, and sometimes meatier than spare ribs . The rack is shorter at one end, due to the natural tapering of a pig's rib cage . The shortest bones are typically only about 3 in (7.6 cm) and the longest is usually about 6 in (15 cm), depending on the size of the hog . A pig side has 15 to 16 ribs (depending on the breed), but usually two or three are left on the shoulder when it is separated from the loin . So, a rack of back ribs contains a minimum of eight ribs (some may be trimmed if damaged), but can include up to 13 ribs, depending on how it has been prepared by the butcher . A typical commercial rack has 10--13 bones . If fewer than 10 bones are present, butchers call them "cheater racks". </P> <Ul> <Li> Spare ribs, also called "spareribs" or "side ribs", are taken from the belly side of the rib cage, below the section of back ribs and above the sternum (breast bone). Spare ribs are flatter and contain more bone than meat, but more fat that can make the ribs more tender than back ribs . The term "spare ribs" is a Middle English corruption (via "sparrib") of "rippspeer", a Low German term that referred to racks of meat being roasted on a turning spit . </Li> <Li> St. Louis style ribs (or St. Louis cut spare ribs) have had the sternum bone, cartilage, and rib tips (see below) removed . The shape is almost rectangular . </Li> <Li> Kansas City style ribs are trimmed less closely than the St. Louis style ribs, and have the hard bone removed . </Li> </Ul> <Li> Spare ribs, also called "spareribs" or "side ribs", are taken from the belly side of the rib cage, below the section of back ribs and above the sternum (breast bone). Spare ribs are flatter and contain more bone than meat, but more fat that can make the ribs more tender than back ribs . The term "spare ribs" is a Middle English corruption (via "sparrib") of "rippspeer", a Low German term that referred to racks of meat being roasted on a turning spit . </Li>

Difference between spare ribs and st louis ribs
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