I started looking at the code on github and found that '0' "Realistic" is more accurate & has a tighter grouping.
Believe me, it was really hard to name those options. In their current (at the moment you wrote here) state, it was like 5+ iterations. OXC engine gives limited space for options' descriptions. The main intention was that "Realistic accuracy shot dispersion" option name implies this option works with Realistic accuracy only. If you want to get "original OXCE dispersion" you shoud disable RA alltogether.
"Normal" in that context means "closer to basic OXCE" - you get wider spread but (hopefully) not that insane 120 degree wide fire cone which you can encounter in base OXCE on a regular basis. "Realistic" means shots will land tightly around a target, with high probability of destroying its cover.
I agree that those options could have better description, I just haven't found the right wording yet.
Here's my recommendation for clarification. Update the text in the advanced options menu to something like the following, otherwise I wouldn't have a clue what either option is doing.
"0> Realistic, higher accuracy, tighter shot dispersion grouping 1> Normal, closer to original OXC logic, lower accuracy and wider shot dispersion."
"lower accuracy" is extremely confusing here, 'cause it stays the same in a game terms. "Tigher/wider shot dispersion" is also confusing - tigher than what? wider than what? What's the base point to count from? I've tried different variants of descriptions (more or less like yours) - and I didn't like them all. That's why I've decided to make them the way they are now... To me, it's better when player gets confused, knows that he got confused, tries both options and determines which one is best for him personally. Instead of player thinking he knows what different options means, but actually being confused by wrong wording.
upd:
my current guess how the description should look like:
Realistic accuracy shot dispersion:
0> Realistic - tight spread, high chance to destroy target cover 1> Normal - tigher than vanilla, wider then "Realistic"