That’s primarily because the Isles 3rd and 4th Leafs are atrocious and all their talent is in the top 2 lines. Whereas the Leafs tried to spread the talent among 3 lines until recently.Barzal's relative xgf% is much better though.
Ignoring PP completely, Barzal produces slightly less primary points in ES but that could mostly be covered by difference in oish%. Matthews might be better, but Barzal is definitely making it a discussion.
He has 2 more primary points at 5v5 in 10 less games. I don’t think it’s balanced out by regression when you are talking 10 less games.