@hybridace101 Both Macs are not designed for gaming because they have integrated low spec. Intel chips. An iMac with AMD or 16" MBP is much better suited, although there are currently issues with the graphics drivers in the 16".
When you did your test did you load the game in the exact same environment, on the same OS build? The same save, same settings, same packs installed, same processes, background tasks and apps running in the background? That would be the only way to get a true comparison.
The MacBook Air will throttle power to avoid overheating thus eventually causing lag in-game. Too much heat over time can also damage hardware.
The 13" MacBook Pro has dual fans to help with better cooling and is not as thin as the MBA so heat will dissipate more effectively.
I cannot recommend either but if I had to choose, I would go with the MacBook Pro.