I assume that what the GP referred to is that even though it's all "beef" (part of a cow's body), one beef product might be mostly tendons, bonemeal and fat, wh

I assume that what the GP referred to is that even though it's all "beef" (part of a cow's body), one beef product might be mostly tendons, bonemeal and fat, while another is a cut of fillet, almost 100% muscle tissue. Colloquially, I think most people would agree that the latter is more pure than the former.