> I'm calling the high level sortDisplayedItems, (or sort_displayed_items) and there's a low level function that ACTUALLY sorts them (as opposed to handling the other bits).

You're absolutely right: naming things is hard. When I was writing Scheme long ago [in university], our convention was to name helper functions with `-helper` in the name:

    sort-foos
    sort-foos-helper
    sort-foos-merge-helper

Now that I write mainly in Python, the convention seems to be to use underscores to indicate things that you should ignore. Usually that's done at a method level, where your consumers are calling the object's public API (sort), so the object's namespace helps reduce such name collisions. The addition of triple-quote docstrings for method comments helps a lot at clarifying purpose as well:

    class FooSorter(object):

        def sort(self, foos):
            """Sort an iterable of Foo objects"""
            # ... sanity-check inputs ...
            self._sort(foos)  # do the sort operation

        def _sort(self, foos):
            """
            Sort things we already know are Foo objects.
            This is a helper for sort(), which already 
            sanity-checked our inputs.
            """
            # do the actual sorting