It’s hard to have an exhaustive list since so many positions have multiple variation (especially guard). Here are a few of the big ones:

Rear mount (a.k.a., back with hooks)
Mount (high and low variations)
Knee mount (a.k.a., knee in the belly)
Side mount (a.k.a., side control)
Turtle
Guard (multiple closed and open variations)
Half-guard
Clinch (many variations)

(Edited once to correct a spelling error)

I'm trying to make a logical sequence
north south
modified side mount
side mount
half mount
reverse half mount
back position
half back mount
back mount
close guard
open guard (delariva, x-guard, butterfly-guard, lasso-guard, 50/50...)
half guard
reverse half guard
reverse guard
reverse mount
reverse knee mount
knee mount
mount
modified mount
reverse back mount
Turtle
.....

I think it's helpful to categorise BJJ positions (This possibly already exists online). This is a non-exhaustive example that disregards any standing positions:

Dominant ground position
- Back mount
- Top mount
- Knee-on-belly
- Side mount
- North South
etc.

Neutral ground positions
- 50/50
- Dogfight
etc.

Defensive ground positions
- Guards (bottom player has some form of leg control on top player)
- Turtle
- Running man
- Panda
- Hawking
- etc.

From my point of view, there are 5 major positions:

1) back mount
2) mount
3) side control
4) standing
5) guard

All other positions you can think of are just variations of these ones.

A huge problem with BJJ is that it is almost impossible to register all the techniques with New stuff coming up every generation, and the fact that people like to renamed things that exist for decades and then saying they invented it....

For me that's a panda

Standing, Guard, and Pin. Then an almost infinite number of variations.