Why are site:siteurl requests different?

Question

Google

Why, if you search site:siteurl, it shows only 5590 url pages, and if you search site:siteurl/, it shows 419000 pages?

Answer 1

From the point of view of an amateur: I checked it on a random site - and it’s true, they are different.
I looked at what exactly is different - I came to the conclusion that, together with /, all objects that fell under the gaze of Google on this site are captured in general, and not a hidden siteurl shows only where the user can get from the main page without jumping past directories that are not available for reading . That is, there are such technical links like: site.org/elements/elem_id_17, there is a link to the element, but the elements directory is not open outside, if you go to site.org/elements/ it will be 404.
Or site.org/img/81231283 .jpg - there is a picture, you can get it through a direct link, but the /img/ directory is not readable. I did not see such links on site:siteurl, but they are full if you add /