why is the output of `du` often so different from `du -b`

Question

why is the output of du often so different from du -b? -b is shorthand for --apparent-size --block-size=1. only using

Answer 1

Compare (for example) du -bm to du -m.

The -b sets --apparent-size --block-size=1, but then the m overrides the block-size to be 1M.

Similar for -bh versus -h: the -bh means --apparent-size --block-size=1 --human-readable, and again the h overrides that block-size.