Difference between ilvl% in Damage done and Ranking

Hi,
Can someone explain me why there is a difference between ilvl% in Damage done and Ranking ?
One exemple :
https://www.warcraftlogs.com/reports/6hGyMWYmq9fxCH3k#fight=2&type=damage-done
Drood “Galline” have for the column “ilv%” the value 80
And for the same fight, in ranking page : Warcraft Logs - Combat Analysis for Warcraft
damage, by bracket “Galline” have 63

The latter view is just a 2 week comparison over all parses. It’s not a ranking.