Disclaimer: I’m not a Stan of either group
I liked how aespa had this underdog spirit and clearly were trying to prove themselves, this being coachella and all. They all sang really well and even debuted new material live which is super hard to do. It’s like they realised how much of an honor it is to be invited to the main stage so they brought their best self.
BP on the other hand felt quite safe in comparison, and it looked more like a victory lap performance so it didn’t resonate as much emotionally. They also played on a smaller stage than aespa so maybe it didn’t give them the same need to prove themselves. I also thought they got overpowered by their (excellent) live band a lot. That said, I like their songs more individually.
Just my 2 cents.