These are acutally analogical parameters to those of RDW and MCV in the red cell count. MPV is the mean volume of platelets that you get when you divite thrombocrit with the number of platelets. PDW is platelet distribution width that describes platelet population. It tells you about the uniformity of platelts, the larger PDW the more extremly small and extremly large platelets are in your sample.

Thank you Mr. Peter for the answer.

these are different parameters. Mean platelet volume (MPV) indicates the platelet size, whereas platelet distribution width (PDW) indicates the distribution of small and big platelets. If the patient has very different-sized platelets, his PDW is high. Otherwise his PDW is low

Thank you everyone for your answer. I was confused about these parameters, but now I am clear.

Thank you dr. Erduran and kubisz

and also palikhe because it was may question, too. but now I understand their difference