His point is that only one of the browsers was using an ad blocker so they were rendering different content because one rendered ads and the other did not.
Oh, I totally missed the part where Opera has the ad blocker turned on by default. Ignore my rambling then; my sleepy brain thought he was talking about two browsers that both had different ad blockers installed.
Not sure if Opera has it on by default - all they say is that it is build-in so that somehow makes it okay to use it and compare apples to oranges :)
If I understand both tests correctly, Opera ran with adblock and battery saver enabled (those are apparently not default settings), versus Edge without adblock, on sites which supposedly are ad-heavy - this will bias the results towards browser with adblock enabled.