Ha, yes, I may have even hijacked another thread on the subject of frosting…..
I would say your first two examples (reply 9) used mechanical abrasion where the item being frosted has also been spun against the abrasive - I assume they are circular with no protrusions such as handles to get in the way.
I believe your second example (reply 10) has also been mechanically abraded but without being rotated. It’s difficult when there is a uniform texture like that so would look for other clues like scratches/feathering out at the edge of the frosted areas, scratches where they shouldn’t be, or low areas that have been bridged by the abrasive tool and not completely frosted.
For example, on your celery, there looks like there might be areas where the abrasive has scratched unintended areas, indicated by my arrow. Is that what you meant by the scratches hitting the clear areas?
…then there is also sand blasting to consider.
Nice pictures by the way, very clear - hope it was ok to draw on one.