The primary difference between % Complete and % Work Complete is that % Complete is calculated based on Duration values while % Work Complete, as the name suggests, is calculated based on the value for Work.
Below are the formulas for calculating the two values:
%Complete = (Actual Duration/Duration)*100
%Work Complete = (Actual Work/Work)*100
If the tasks in your project are of type ‘Fixed Work’, then you will be entering the estimates for your tasks in the Work column. This is what I do in my software projects. Microsoft Project (2007) will automatically calculate the value for the Duration of the tasks based on the formula Work = Duration * Units.
In this case, you will be reporting the progress of your tasks as Actual Work done (data will be entered in the Actual Work column) and Microsoft Project (2007) will automatically calculate the % Work Complete based on the value for Work (the initial estimate for the task) and the Actual Work value (actual work completed since the start of work on the task).
On the other hand, you may be entering the estimates for you tasks as Duration values (Work is automatically calculated by Microsoft Project). In this case you will tracking progress on your tasks as duration elapsed or Actual Duration (tracking data will be entered in the Actual Duration column). In this case Microsoft Project (2007) will automatically calculate % Complete based on your values for Duration and Actual Duration.
