What's the difference between refiling and archiving? Isn't archiving just basically the same as refiling to an archive file?

I have not gotten into working with either of these command sets yet. I'm just reading about them and would just like to know the difference at a conceptual level.

Archiving also adds some auxiliary information to the archived entry, like the date of being archived, from which file it came, etc.

Yes, archiving is a special kind of refiling. I use refiling to organize my org files, moving items between files or inside a given file. Archive is when I'm done with an item, I'm using "archive to subtree" so I know where it's gone and it's also hidden by default.