Coverage describes how much visible variation the foundation is designed to conceal or even out. It is not a ranking of product quality.
Light, Medium or Full Foundation Coverage: What Is the Difference?
Light coverage generally allows more natural skin characteristics to remain visible.
Medium coverage provides more evening while retaining some natural appearance and may be buildable depending on the formula.
Full coverage aims to conceal more visible variation, but it does not automatically mean a heavy or unnatural finish.
Coverage and finish are different. Finish describes the final visual effect, such as matte, natural or radiant.
Choose according to the result, comfort and occasion you prefer. See How to Choose the Right Foundation Shade before finalising your colour selection.