We know Max has always been fast, but hot headed. A lot of incidents he's been in were because of him trying to force the issue and causing contact. For the most part, he's cleaned that up since the 2nd 1/2 of last season. While the Honda PU is better, it still isn't a match for Mercedes and Ferrari, but he's managed to overachieve in that RB and stay sniffing at the podium (even if it may just be 3rd, which means he managed to split the top two teams). Considering how much faster and consistent he is than his teammate Gasley (who I wouldn't be shocked if he got bumped back to TR and Kvyaat moved back up), there's not much more Max can do to improve.
Vettel, on the other hand, could be considered on a downward slide the past few seasons (or since he got to Ferrari, if you want to me harsh). We've seen over the past 2+ seasons when the pressure gets on him he cracks. Crashing out in Singapore, wiping out in Germany, taking himself out of races with spins when he really needs a win (or at least a points finish) seem to be the norm. Leclerc has more than been a match for him in his first few races at Ferrari, and while he has benefited from being the senior driver in team orders, he hasn't been able to turn that into wins. Even with an obvious HP advantage, Vettel is only ahead of Verstappen by 11 points. If Vettel has more races like Paul Ricard, I wouldn't be surprised if Max beats him.
Admittedly, it's still early, and Ferrari could possibly sort out why Mercedes is faster (or at least more consistent) on race day when Ferrari has the power advantage. But even then, we've seen Vettel in a great car crack when he gets pressed in the race. Hamilton never cracks. The new Max looks to have shaken his habits off, but who knows. Vettel has won 4 titles, but those years RB had far and away the best car on the track, so he was rarely challenged. Now that he is? You have to wonder, juts a little bit, exactly how good he is
<-- Dave Thomas knows what's up...
Jay: Look here homie, any nigga can get a hit record. This here is about respect.
Game: Like Gladys Knight.
Jay: Aretha Franklin.
Game: Word, I like her too.