There's a lot of changes, including the length of some of her hair, a major redo on the whole face, shading changes, depth to the hair strands, major changes to the handle of the...uh...whatever that is, and her left pinkie was given the proper number of knuckles.
To check revisions, I open the original files in separate tabs; to do this with Danbooru, click the file size of the image. Then I jump between the tabs and let my eyes catch the differences. Up until recently it was hard to compare a Danbooru image to one on Pixiv due to zoom level wonkiness, but that seems to have changed.
You can "do a diff" in Photoshop to find changes too, but :effort:
