What does mean differential panel auto dif? thanks

Types of WBC's: The machine in the lab automatically counts the different types of white blood cells (wbc's), so the results are listed under auto diff.

Just that: The differential, that is the percentage of the different subtypes of wbcs, has been performed by the hematology instrument, not the med tech counting 100 cells under the microscope.

CBC: When you get a CBC (complete blood count), the white cells, red cells, platelets and many parameters of cell size, shape, and volume are reported. In addition, all of the many differant kinds of white cells are reported. In the old days, a human being peered into a microscope and counted them one at a time. Nowadays a machine does this automatically - hence an "auto diff".