Running a report returns very different results between Actual Hours and Total Hours.
Cause & Resolution
Actual Hours reflect the exact hours logged.
Total Hours is the rounded sum of all hours on the project, the last time the project finances were last calculated.
If the Total Hours appears significantly different than the Actual Hours field, go to the Project Actions and select Recalculate Finances to update the Total Hours field.
You can bulk edit multiple projects by selecting them from a list of projects and choosing edit. Scroll down to the Settings section and check the box for "Recalculate Costs and Revenues" and then click Save Changes.
For additional information on Recalculating Finances please see this document: Prevent "Recalculate Finances" From Affecting Historic Hours