Honestly it’s hard to pick a specific thing that’s different between Shattered and the original Pixel Dungeon, there are fewer things that are similar at this point! Almost everything is different gameplay-wise aside from the very core gameplay loop, but if you’d like a little summary of the biggest visual changes I did write a blog post about that semi-recently: https://shatteredpixel.com/blog/ten-years-of-shattered-pixel-dungeon.html