Good question! The regular sprite style will basically be like the demo but fully updated and redone. Essentially a mix of the two! As for CGs and backgrounds, those are close to the prologue, but a lot more detailed and fully fleshed out — what you'd expect from the demo.
Mechanically, you can expect the narration and dialogue styles to be just like the prologue, but there are a lot more interactive elements that carry over from the demo when you're playing as B.
You'll get a better picture of how everything will look in upcoming promo material we have planned, so please keep an eye out for it!