My 2014 got warm but never too hot on my lap but when I got the 2019 i9 it was unbearable to put on my lap without some kind of insulation. Now my M1 Max barely feels warm at all on my lap, often cold and the battery is really something else.
Sometimes I play Factorio sitting on my couch and with my 2014/2019 MBP I HAD to have the power cord nearby. Obviously I could go on battery for a while but as a rule I always plugged it in while using (see also: I LOVE having magsafe back, the 2019 always made me super anxious with only having USB-C for charging). Now with my M1 Max I can go for hours playing without thinking about power.
Likewise when I go up to see my parents/family I can jump on my laptop a number of times for quick tasks (~2-3 hours over a few days) and I never have to think about plugging it in. Maybe it was something I had installed on my 2014/2019 MBP but I felt like those discharged faster when not in use. My M1 Max feels much closer to an iPad where you can leave it unused for days and come back to still having 80%+ battery.