Final answer:
The difference between the Estimate to Complete and the Estimate at Completion forecasts is best described as the Variance at Completion, which is a prediction of whether the project will be over or under budget at the end of the project.
Step-by-step explanation:
The difference between the Estimate to Complete (ETC) and the Estimate at Completion (EAC) can best be described as the Variance at Completion (VAC). The ETC is a forecast of the additional cost required to complete the project, whereas the EAC is the forecast of the total cost of the project at completion. The VAC is therefore a calculation of the difference between the EAC and the actual cost to date, which indicates whether the project will be over or under budget upon completion.