The color of blood cells as seen in these transparencies is determined by several factors: how the microscope slide was stained, the filter(s) used during photography, and the extent to which color has faded in the original and/or on the 35 mm slides that were digitized (blues are particularly prone to fade more than other shades).
The apparent size of cells is determined to some extent by the thickness of the blood smear - in a very thick smear, where cells overlap significantly, the apparent diameter of white cells appears somewhat reduced. Focus on such "thick" cells is often less than optimum. In this instance the microscope slide is superior to the transparency because you can focus up and down.
Some cells on your microscope slide, and even some in these transparencies, may not be identifiable at all; other cells may be very difficult to identify, yet one might prefer one alternative over another. The point of the exercise here is to learn and understand the major characteristices of the different cell types so that when you are faced with a cell which is difficult to identify with certainty you can, nevertheless, enumerate the reasons why one might consider this cell to be of one type rather than another.