Ngl, I've never had issues with either for ram. my experience with Firefox is mostly the sameas chrome with ram usage. The main reason Im on Firefox is cause it's been a whole lot more stable for me than chrome.
I switched from Chrome to Firefox on my Mac desktop and the memory usage was cut in half at least. I only use it on my Linux notebook, so I have no idea about the memory usage difference there, but there was an unquestionable difference on the Mac. It has 16 gb of ram and is from 7 years ago, so it was before the M-chips and their ram hunger and still gave me memory warnings.
Now I never have memory issues on it. All it took was switching to Firefox.
So it definitely makes a difference on some systems.
If the majority of ram isn't being utilized you either have a problem or have entirely to much ram. I'm not saying programs can't be memory hogs, but they should utilize what resources are there to perform better. It would be like turning on a flash light, using all of the power and then covering half the bulb while trying to cross a field in the dark. The CPU and GPU use more electricity when running at higher percentages, ram is negligible for the most part.
i always hear this but it's obviously not true lol, if i ever see my ram reach max usage the computer shits itself and i'll likely have to restart it because most things become utterly frozen
full RAM utilization is patently not something you want.
In my personal experience chrome rarely gives up ram and will starve programs that need it more. While that works if you're only running chrome, if you're using it in the background while doing something else then you can find important programs running out of memory. The result is that you have to close and reopen chrome.
Granted, I haven't used chrome or a chromium-based browser in a very long time, so chrome might have gotten better at giving up memory when other programs need it. However, if I'm playing a game, doing rendering, working in a game engine, etc, then usually I have a browser open in the background with YouTube or Twitch and/or programming/visual references. I don't need or want a browser consuming as much memory as it can, just enough for it to play videos, show me reference images or tell me how to program something. It absolutely doesn't need +8gb of ram to do that (I saw it hit 16gb once, which was when I switched to Firefox; 16gb is ridiculous no matter how many tabs you have open).