"file::url" and "file::version" - what, when?

[rasteiner]

I don’t really get the difference between the file::url and file::version components.
It seems like they kinda do the same, but both are needed:
https://github.com/getkirby/getkirby.com/blob/master/site/plugins/cloudinary/index.php#L44

But I didn’t find any documentation for file::version