What's the diffrence between vfs-read-chunk-size and vfs-read-ahead?

I tried reading the docs, but I still don't get it. It seems like they kinda do the same thing. When using vfs-read-chunk-size along with vfs-read-chunk-size-limit isn't that kinda the same things as just using vfs-read-ahead?

Those are range requests to download something from a remote regardless of cache mode on/off/full/writes/minimal/etc.

This is particular to vfs cache mode full and works to read ahead for caching purposes.