Before the Apple Silicon macs were introduced a few days ago, here was the difference between the mac mini and the MacBook air
intel macbook air has: built-in retina display, keyboard, trackpad, webcam, microphone, battery system
intel mac mini has: more capable processor, RAM DIMM slots, additional thunderbolt/usb-c ports (4 vs 2), usb-a ports, ethernet, HDMI
But now with the M1 machines, the mac mini has the same processor (or close enough, 7 vs 8 GPU cores), the same memory, the same thunderbolt/usb-c ports. The only things it has that the MacBook air doesn't are usb-a ports, ethernet, and HDMI (all of which can be added to the MacBook air via a cheap USB-C hub with pass-through power, such as this one https://amzn.com/B08C9HZ5YT for $35). That and an active cooling system. There are advantages, but they are pretty slim.
I'm a mac mini guy. My main machine is a mac mini. My wife, parents, in-laws, and uncle also use a mac mini. But I don't know if I can recommend the M1 mac mini over the M1 MacBook air. The MacBook air is $300 more ($335 more if you include the cheap USB-C hub) and you get a lot for the extra $300.
Obviously, if you already have a quality pair of 4K displays that you want to drive, then the M1 mac mini makes sense for you. I'm not saying there aren't people that would prefer the mini. But it seems like there are fewer of those people now.
intel macbook air has: built-in retina display, keyboard, trackpad, webcam, microphone, battery system
intel mac mini has: more capable processor, RAM DIMM slots, additional thunderbolt/usb-c ports (4 vs 2), usb-a ports, ethernet, HDMI
But now with the M1 machines, the mac mini has the same processor (or close enough, 7 vs 8 GPU cores), the same memory, the same thunderbolt/usb-c ports. The only things it has that the MacBook air doesn't are usb-a ports, ethernet, and HDMI (all of which can be added to the MacBook air via a cheap USB-C hub with pass-through power, such as this one https://amzn.com/B08C9HZ5YT for $35). That and an active cooling system. There are advantages, but they are pretty slim.
I'm a mac mini guy. My main machine is a mac mini. My wife, parents, in-laws, and uncle also use a mac mini. But I don't know if I can recommend the M1 mac mini over the M1 MacBook air. The MacBook air is $300 more ($335 more if you include the cheap USB-C hub) and you get a lot for the extra $300.
Obviously, if you already have a quality pair of 4K displays that you want to drive, then the M1 mac mini makes sense for you. I'm not saying there aren't people that would prefer the mini. But it seems like there are fewer of those people now.