What are Mouse Acceleration profiles in the gnome-tweak-tool?

I am running Ubuntu 18.04 and I could have sworn that in previous GNOME versions that the Mouse Acceleration profiles option wasn't there. So I am now rather intrigued into what they are and if they are only for the mouse or if they are also for the touchpad. It is currently set to Default, however there are three options:

• Adaptive
• Default
• Flat

I have tried them all but there doesn't seem to really be any difference. But perhaps that it because they only apply to the mouse (which I lack) and not the touchpad? Anyhow, what exactly are they? And what do the different ones do?

Some digging unearthed information that is "for developers and is not necessarily useful for users".

After trying the different settings, I experienced:

1. adaptive - Less precise than other modes while moving the mouse slowly or quickly. It's quite jittery.

2. default: Very smooth and accurate when moving short distances. If I move the pointer across the screen I'll occasionally overreach the target. This mode basically seems to begin with a slow acceleration and increase as the mouses speed increases.

3. flat: There is no acceleration. Moving short distances results in less precision than the default profile, but I can anticipate where the pointer will be a bit better when moving over large distances, which helps avoid the overreach. I read here that when playing FPS games you want this profile.