differentiation
In geology, differentiation is a process that takes place in a molten or partially molten planetary body by which heavier materials sink to the center and lighter ones rise to the surface. In Earth's case, differentiation resulted in an iron-nickel core and a crust and mantle rich in silicate rocks.
In embryology, differentiation is the process in embryonic development during which unspecialized cells or tissues become specialized for particular functions. In oncology, the degree of similarity or difference of tumor cells to the structure of the organ from which the tumor arose.
In mathematics, differentiation is the method by which the derivative of a function is found.