As nouns the difference between taxonomy and osteoclast
is that taxonomy is the science or the technique used to make a classification while osteoclast is (physiology|cytology) a large multinuclear cell associated with the resorption of bone.
As nouns the difference between osteoclast and osteoprotegerin
is that osteoclast is (physiology|cytology) a large multinuclear cell associated with the resorption of bone while osteoprotegerin is a cytokine that can inhibit the production of osteoclasts.