Currently both lists are not orderable (see LPS-54460), however the UI displays a link in the Name column like if they were orderable by name.
The link in each list should be removed until the LPS-54460 is implemented.
Support for ordering by name in lists of Site templates and Page templates
Site and Page Templates are not in alphabetical order
Link for 'Order by Name' on page templates and site templates do not work
Find an alternative to storing localised fields as an XML in a DB column