The "Current Grade Distribution" chart is shown when a class uses weighted grading. This chart indicates which categories are contributing most, if at all, to your overall class grade. If a weight is not shown on this chart but is shown in the "Weight Distribution" chart, that means no grades for that weight have yet been recorded in Helium.

This graph is a sort of progress report for your current grade as you work your way through the semester. It will likely closely match the "Weight Distribution" chart. In fact if you were to receive 100% on every assignment for every category, this chart would be identical to the "Weight Distribution" chart. When trying to understand what assignment grades will have the most impact on your current grade, this chart is more relevant than the "Weight Distribution" chart.