Final answer:
CD45 is a glycoprotein used to identify and distinguish white blood cells, along with CD4 and CD8, which serve different functions.
Step-by-step explanation:
A CD45 molecule is a glycoprotein used to identify and distinguish white blood cells. CD4 and CD8 are also glycoproteins used to differentiate between types of white blood cells, but they serve different functions. CD4 is expressed on the surface of Helper T cells and regulatory T cells, while CD8 is expressed on the surface of cytotoxic T cells.