get_instructing_sections is per user and only for the explicit assignments. "Get all course sections for Spring 2014 which have an instructor record for Chris."

get_course_secondary_sections is per course and gets all sections for the course, regardless of whether anyone is explicitly assigned to teach them or not. "Get all secondary sections for CHEM 1A in Spring 2014."

The driving requirement is that we very often have secondary sections without an explicit instructor record, but which are associated with a primary section which *does* have an explicit instructor record.