There are other people in this thread saying that there are no A/B scenarios in this game though. He claims the part he missed also has little new content.
I was watching Skill Up's 100% spoiler free review and he states the A and B scenarios differ vastly, and used Nier Automata as an example where RE2 makes more significant changes the second time around opposed to Nier's multiple playthroughs (between 2B and 9S). He does say that when you replay the game for the 3rd and 4th time then there aren't that many changes. So I'm confused by the whole thing. To me it does sound like the A and B scenario differ vastly from each other.