Check out IPS and MiniLED specifications.
The latter is in some sense the same IPS, but already with full
black (than 0.42 cd/m² on IPS).
Subjectively, when you use OLED-like screens for some time (on phones, for example), you don't really want to go back to regular IPS.
If you are unable to compare both laptops live, then at least try to compare two business phones (preferably from the same manufacturer) where one screen is IPS and the other is AMOLED. Sometimes it takes time to understand the difference.
But, NB preliminarily notes that OLED can consume
three times more energy to display full white color than IPS screens.
I think that these estimates are still preliminary, because various factors "play" here, such as the nature of use: do you only surf the web on dark-colored sites? How many colors will be displayed in total, and what "color mode" is selected?
So here it makes sense to think if there can be significant differences in autonomy. (Remember, the screen is not the only thing that consumes battery power).