Police officers prefer Donut charts where most other governmental employees prefer Pie charts .
Besides that... No difference that I know off.
A donut chart functions precisely like a pie chart. The only difference is that the center is blank.
While this allows for space for a label or icon, it tends to make the chart more difficult to read. One of the key ways a viewer interprets a pie chart is by studying the angles of the sections at the point where all the lines intersect. Because the hole in a donut chart gets rid of these angles, a donut chart is harder to read.
No difference as such just the appearance you can show both to your client and keep which he is comfortable with like below:
Donut charts and pie charts are basically the same, except that in additon to slice size & color pie charts include angles that can be evaluated to make more sense of the data. Both charts are typically used for the comparison of a part to the whole.
Bottom line is to design with your user in mind, would they benefit from the larger 'pie slices' of a pie chart or the 'white spaces' of a donut chart?