Differences between plugin and add_cap() function

Helo

I don’t understand one thing. I would like the user to have access to the list of users (without administrators).

When I do something like this:
add_role( ‘testrole’, ‘testrole’);

$test_role = get_role(‘testrole’);
$test_role->add_cap(‘list_users’);

the user also sees administrators in the user list.

When I add a role using the User Role Editor plugin and add list_users cap, the user has access to the list of regular users only.

What is the difference between these two situations?

Additionally, if I add a role via code, all I have to do is enable the plugin so that only regular users appear in the list (without admins).