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The major difference between Levi's 550 and 551 jeans is that Levi no longer sells the 551 line through its online store and the 551 brand is no longer carried by major retailers. Both the 550 and 551 jean lines are a type of classic, relaxed-fit jeans with a tapered leg. Unlike popular flared and boot-cut jeans, the 550 and 551 jeans follow the contour of the calf and taper at the ankle.

Levi's 551 jeans

Popular in the 1990s, the Levi 551 line of jeans is no longer carried by Levi's website and cannot be found in major retail stores. Levi's 551 jeans came in a variety of colors, including blue, light blue, acid-washed and black and had five pockets like the newer 550 version of the tapered fit jean. Levi's 551 had a zipper fly and also were sold as shorts.

Levi's 550 jeans

The 550 jeans are a line of relaxed fit, tapered jeans, not unlike the 551s. The 550 is a classic cut that sits at the waist and offers maximum ease through the hip and thigh, tapering below the knee to the ankle. It has classic five-pocket styling and is 83 percent cotton, 17 percent recycled cotton and 10.75 ounces of imported materials.

Substitutes for the 551

Levi's website recommends that customers try the newer 550 style for a comparable fit. Although they are a separate jean line, the 550 and 551 have a similar taper, pocket count and general fit.

Vintage 551 jeans

Finding a new pair of 551 jeans could be difficult, but customers interested in vintage 551s can find them online for anywhere from $4 to $30. Many used pairs of Levi's 551 are sold at online marketplaces like eBay.