To be honest I don;t think there are any other CMS’s who handle user/admin access/security in the same way.
The way MODx’s system works is to allow you to add various groups which have various abilities within the manager and the site (Manager groups) so that you can perhaps havea group of folks who can only edit, not create or delete pages for example, or have a group set up solely for editing web users (frontend users) for the purposes of banning problem users for example.
Then there’s the web users, which when you combine them with document groups, you can allow people into certain sections of the site that others can’t access.
You can also (if memory serves) apply document groups to
individual web users as well which has it’s uses.
There’s plenty of things you could do with this, such as have content available for paid subscribers and have hidden sections for site staff that don’t neccessarily need to access the Manager area to name a couple.
It’s a powerful, novel approach if somewhat confusing the first time you try and get your head around it
But yeah, I don’t think any other CMS does it in quite the same way. Usually it’s a lot more difficult to give individuals specific permissions in this way.