According to the API, implimentation details of this method is PEGA private. so you'll be only able to guess how it works by looking at the parameters. You can get an idea by looking at Work-ComparePages activity Java step. PEGA does not promote the use of this method.
Sorry I did not completely undestand your question. However I believe using\analysing "rulebase compare" feature in PEGA would help (DesignerStudio-->System-->Tools-->Refactor Rulesets-->Rulebase compare)
we dont have any provision to compare a rule with all its old versions.
But you can compare 2 version of a rule by using Rule Diff utility which is available in the Pega > System > Tools > Refactor Rules > Compare Rules (you can select the rule from any 2 versions). I hope this helps you :)