Battery life for various OS & UI

[lat]

Can battery life be gained by a choice of OS & UI?

1. Is there a noticeable difference in battery life between operating systems?  (All other things being equal, of course, like usage.)
   I'm especially curious about Archlinux vs postmarketOS vs Debian.
   
   
2. Does UI choice notably affect battery life?  Which UI's are least/most power hungry?
   

My hypothesis is that minimalistic OS's like PMOS load cpu less than, say, Ubuntu/Debian or Manjaro, and thus draw less power.

Likewise, for UI's, I assume that a bare OS only with command line interface and without any GUI uses less power than, say, Lomiri (Ubuntu Touch) or Phosh.

I haven't done any solid testing, though.  From casual use, SXMO did seem to have a noticeably longer battery life than ArchLinux+Phosh.

Maybe people could share their experiences with battery life using different OS's & UI's here?