Hard for me to make a good comparison, partly because I don't get to watch Burrow most of the time. Seems the Chiefs are often a national slot or a SNF/MNF game. At any rate, I watch Mahomes a fair bit.
The Chiefs feel like a more "coherent" team to me. I get what they are and what they want to do, the coach has a plan, he manages the game, the pieces are there. Mahomes has a lot of help around him. I like their WRs pretty well as a group, and Kelce is a flat out cheat code. However, what I really like is the OL....they usually look really good. CEH added a nice touch at RB and now this Pacheco guy is really something. All that said, as noted in my last post, Mahomes is really, really, really good. Like, it's hard to process all the tools he has to win a game.
When I do get to watch the Bengals, Burrow has usually been hopelessly obliterated by a line that would make RG3 have sympathy for him. Although they do win their share of games. Sometimes it's his fault for not getting rid of the ball quicker. Most of the time it's not. Otoh, the Bengals line looked uncharacteristically good against Buffalo. Beyond that, Jefferson and Higgins are quite a pair to have to throw to, and Hurst is not a bad TE himself, although nothing like Kelce. I also don't think much of Zak Taylor as a coach, but that's just me and I could be wrong. Really different team than the Chiefs.
The two QBs work in such different situations that comparing them is hard, so I don't. Easier to just look at the tools they display. Mahomes can simply do everything, most of it at an uncommonly good level. I don't have a good feel for what Burrow does (or doesn't do) that would put him near that level, or not. When I do get to watch, he's usually either cremated by a rusher or he throws to a wide open receiver. How much is the former bad play design or a poor OL, and how much is the latter good play design or a next-level receiver? I feel like I can see what Mahomes is when I watch the Chiefs. I can't tell what's Burrow and what's not, be it when the Bengals are struggling or when they're doing well. He can find wide open receivers and complete some checkdowns. Okay, fine. Can he do more? I don't know, I don't get to see it. Mahomes, on the other hand, is a never ending highlight reel.