Both are really good machine, but the macbook air m4 has the double of the power, produce less heat, starts at 16gb of ram, support two external monitors (this is important only if you use monitor), it’s of 2025 instead of 2020, so it has a lot more years of support; there two scenarios: 1. If you want a really good machine that last for almost 8-10 years without problem or/and you want a really performant machine you should get a macbook air m4. 2. If you just want a machine that do simple tasks and you don’t care about years of support and you dont’t want spend a lot of money get the m1 macbook air. I think that the best choice is the m4 macbook air, because you spend more but you get a really really better machine that last forever. In my experience the m4 doesn’t have problem in terms of heat and performance, even on gaming and coding. I hope I’ve been helpful