They have better battery life than most laptops, but it also strongly depends on what configuration you use and what you’re doing. For instance, my M1 Max laptop has never hit its stated battery life and frankly is pretty close to my AMD laptop (when its battery wasn’t half dead). The AMD laptop is admittedly heavier though.

AFAIK they’re about the same as the M4 in terms of battery life. If you look at their marketing, their battery life improvements are based on their Intel and M1 laptops (whose owners they seem to be targeting for upgrades).