Long post incoming so bare with me, but outside of watching both extensively with my own eyes, here's what the numbers say.
Antony
His xG is high mainly because he shoots a ton, as he's in the 95th percentile of all AM's/wingers for shots attempted per 90. But goalscoring/shoddy finishing isn't my main issue with Antony, as many young wingers are very hit or miss in front of goal (even though he shoots too often).
Amad
Amad has been more productive this year so it's no surprise he looks a bit better on the surface with these numbers. The nice part is that he's already outperforming his xG, which is impressive for a young player with as many goals as he has this year let alone someone that isn't even a striker. But I don't expect either player to be (hopefully) relied upon as a main source of goals next year for us, so let's dig deeper and see what really sets the two apart.
Antony
Those passing stats are shocking, especially from a player that isn't very creative either. At the very least you'd want to seem him circulating the ball more to our main creators, but this shows that he's a bit of a black hole which matches up what we see in game.
Amad Diallo
Well that's a big difference. Amad not only shows a more willing tendency to pass and combine with others (as well as being more successful at it via %), but he's notably far more progressive in his passes than Antony. He more than doubles him in passes into the final third and general progressive passes are over 1 full pass more per 90. Neither player is uber creative in fashioning actual scoring chances, but Amad shows far more ability to find other players with forward passes while keeping the tempo high. This is vital, as we need more technical ability in our team and the ability to accurately pass forward, while seemingly a simple skill, is often lacking within our side. You don't need every player in the side to be a Bruno-like wizard at creating and assisting, but you certainly need all of them to have the confidence to play passes in tight spaces to find gaps against the more well drilled or higher pressing sides.
Antony
Amad Diallo
Finally we get to dribbling/possession stats on ball. Antony is actually very tough to dispossess, which matches what we all see each match day. For all his faults, he does manage to wriggle out of difficult situations while keeping the ball and does so clearly better than Amad at this time. However, you can also see that Amad gets on the ball far more in general, especially in the middle third of the pitch, and while he isn't Garnacho running at his man he's more willing and successful in taking on his man than Antony currently.
So to sum up: All of this reinforces the fact that while Amad is young and inexperienced, and obviously playing in an easier league, he's undoubtably more comfortable/talented both in front of goal and in the build up of attacking play. Which shows when you watch both, as Amad seems to just have more to his game while Antony is a one dimensional "shoot first" type winger that isn't efficient with his shots at all. In reality his best qualities for us currently are that he works very hard in tracking back and doesn't lose possession needlessly. While I appreciate those things, that doesn't scream "huge prospect that we need to keep as an automatic starter and give endless chances to". I'd feel differently about Antony if he had the take-on ability of Garnacho or some uber-young raw winger, as at least then you'd see a path for him to one day put it together with improved decision making/end product, but he doesn't. If he can't improve his overall play aside from shooting he's not going to make it here, or worse: we'll persist far too long while shunting a promising prospect to the side just because ETH/the club feels the need to "give him more time" because he cost 80m. And I don't think this is a one off, as many raised similar concerns about Antony even while he was at Ajax. He was never a Memphis type that just tonked a weak league, and his underlying metrics have always been quite average compared to the hype he had even before we signed him.