A little help understanding.

Something I really dont understand, is that. How can a that has the exact same runes, and exact same build, with the same level, about the same KDA (one is not more fed then the other) have 80 AD more then what I have? Keep in mind, this was a match where infernal drakes was not in them.

I cant understand that, everything is just the same, but she kills me in 3 autos, and I need at least 6 or 7 autos to kill her. I dont understand that, tried to get the same AD as her in practice tool, not even close to the numbers she had.