Its actually $200 dollars difference between the 11 ($599) and the 12 ($799). The iphone 12 mini is $699 but the screen is half an inch smaller.
The 12 will have slightly better battery life, 5G (honestly I don’t think the tech is mature enough to worry about just yet), the fancy magnetic connector on the back, slightly better cameras etc.
If you can live with out attaching accessorizes to the back of the phone Id probably recommend the 11 and save the 200 buck.