Burn Up Chart : Burn Up chart will show if there is a change due to estimation or scope creep.
Burn Down Chart - In Burn down chart we can't find out If the change is because of scope creep or estimation.
In Above Diagram if three is a change in TGT (target) then it means that PO has made some changes in scope.
From Chart # 4 (Burn down chart) it is not clear if there is a spike because of estimation being incorrect or due to scope creep. So Burn Up Chart provide more useful information than Burn Down Chart.
