The difference between supplements with glucosamine, chondroitin, MSM...?

This was the question. However, just because that's the product you're asking about, doesn't mean that's really what you need. "Achy legs" are not likely to benefit from any of these, unless there's actual pain in the joints from some degenerative process. Turns out the young lady was in need of support hose, not glucosamine. The average person really does need a good pharmacist to help them understand these things. Another life improved with pharmaceutical care!