F-critical is the one you are comparing to. F-stat is the one you calculated based on your data and F-critical is a fixed value based on your degree of freedom. For example, you will use F-stat to compare to F-critical value at 95%, if F-stat>F-critical, then P<0.05. If you use F-stat to compare to F-critical value at 90%, and F-stat>F-critical, then P<0.10. Hope it helps!