Let's say you have a porcelain vase.
If you drop it on the ground and it breaks into 10 pieces, the vase still exists, but it is broken. You may even glue the pieces back together, and it would still be the same vase.
But if you take a hammer and start pounding away at those pieces, at some point the vase ceases to exist. Whatever it is that made that porcelain dust a vase is gone forever, despite every molecule that was in that vase still existing.
It is not something you can quantify scientifically.