Left is brighter, that decides the first impression. The size of the images is too small (for me) to try to judge which photo is actually better. I trust that the Pro has the more capable camera system.
iPhone 12 128GB vs iPhone 12 Pro 128GB would be a fair comparison. Price $879 vs $999 (SIM free).
Differences: Camera system, RAM (4GB vs 6GB), display brightness, exterior and colours, weight (162g-189g)
I think it is a close decision. But if I would buy one, it would probably be the 12 mini despite the weaker battery.