Never use tasks with time estimates. Ever. There are many reasons for this.
It's not Agile, for one. We use "working software" not "completed tasks" as a primary measure of progress
Estimating in absolute time is impossible. Even if it weren't, your time does not equal my time
It's a recipe for old command and control behavior
It is no different than a ...
I believe that the discrepancy you are seeing is caused by the two figures using different figures for capacity. This is just an educated guess but it looks as though the work details tab is using capacity at the start of the day, while the chart is using capacity at the end of the day.
If I'm correct, you can interpret the figures as follows.
From the ...