Demographic and Statistical Reports, such as the Statistical Report and the Tallies Report, have columns with the values of Number of Donors and the Number of Constituents. This solution describes the differences between these fields.
# of Donors: This includes the number of constituents that have actually given at least one gift within the parameters specified in the report, such as gift dates, soft credit and matching gift settings and selected gift types. All donors are constituents.
# of Constituents: This includes the number of constituents, whether or not a gift has been given within the parameters of the report. This can include both donors and non-donors.