Josh Leivo is actually not even an even comparison in my opinion.
Their last season's NHLe adjusted for 82 games:
Vesey:
14 goals + 12 assists = 26 points
Leivo:
13 goals + 23 assists = 36 points.
Leivo also scored 5 points in 12 NHL games, which is in line with his NHLe. He was on pace for 34 points. Considering the amount of pro experience as well, in my opinion Leivo is a much better prospect. And even then he's for some reason not nearly as highly touted as Vesey.
Really, most people seem to only look at the best-case scenarios for comparison points. They for some reason seem to enjoy ignoring the comparisons of Vesey to undrafted NCAA players who never become pros. He was only 8th in PPG this season, in the weakest division in all of NCAA. And it's not like he's younger than his peers, either. I do not at all understand why teams would guarantee top 6 spots for a player like him. I see him as a player who can only play a top 6 role but who cannot play well enough to get it in NHL.
If he was better than I'm saying, he'd have scored much better in the weakest NCAA division especially when we consider how old he is. He barely outscored Kalle Kossila who is undrafted and as whatever-tier as they get and nowhere near NHL. Kalle Kossila also was playing in a significantly tougher division and his NHLe is much better for last season(Kalle Kossila's NHLe is 11 + 33 = 44). They are the same age.