Why is ls and du showing different sizes?
When there is a difference in sizes between the two commands it means that the file is a sparse file:

ls is reporting the allocated size
du is reporting the space actually used

A sparse file is a file that is mapped to use a certain amount of space but may not currently be using that space.

Source:
https://en.wikipedia.org/wiki/Sparse_filehttps://en.wikipedia.org/wiki/Sparse_file