A question from a non-Airbus and non-ETOPS guy: Is there a difference in systems between an ETOPS and a non-ETOPS A321, or is it "just" a regulatory thing?
It's also a maintenance and operations difference.
EG. Checking the IDG oil level and filter bypass pop out indicator before each flight.
All certifying maintenance personnel need to undertake regular ETOPS continuation and awareness training.
All critical components need to be certified as ETOPS compliant etc.