Adventurer Rings discussion

What mainly confuzes me is the fact that there are 2 explainations on how this crit works. One theory sais the critical is just adding more chance (5% for the cruel ring) while the crits also do more damage (20 % for the cruel ring).
the other explaination sais these crits work seperate, meaning you can get 4 types of damage -> normal damage, ring crits on top of normal damage, ring crits on top of critical, and critical without ring crits.
if you would be an aran, with 60% base crit + se (15%) + 10% crit ring + 10% purple arcglaive (durability weapon) this would be 95% chance on critical with the first theory... with a sick high damage multiplier for crits..